9.2.1
-
Finished your HSC? Check out our University Discussion, Non-School forums or help out next year's HSC students! -
YOU can help the next generation of students in the community! Share your trial papers and notes on our Notes & Resources page
State Rankers! (1 Viewer)
- Thread starter powlmao
- Start date
Sanical
SpiderAnderson
chem contexts 2
Mate all i meant was it reminds me of course i did and have seen which probably was in year 10. You do learn about CFC in year 10
My notes for chem
Chemistry Revision – Module 1 – Chemical Earth
1.1 Construct word and balanced formulae equations of chemical reactions as they are encountered
1.7 Apply systematic naming of inorganic compounds as they are encountered in the laboratory
> IDE = compounds composed of two elements only
> ATE = compounds that contain oxygen
> PER = compounds that contain extra atoms of one of the elements
> Method for writing a two element compound:
1.2 Identify the difference between elements, compounds and mixtures in terms of the particle theory
> Particle theory: The kinetic theory of matter (particle theory) says that all matter consists of many, very small particles which are constantly moving or in a continual state of motion.
> Element: a substance that cannot be broken down into a simpler substance.
> Compound: two or more elements chemically combined and that can be broken down into its simpler substances by chemical means
> Mixture: two or more substances NOT chemically combined and that can be broken down by physical means.
1.3 Identify that the biosphere, lithosphere, hydrosphere and atmosphere contain examples of mixtures of elements and compounds.
> Biosphere: oxygen, silicon, aluminium, iron, calcium. Living organisms are organic (carbon-based). Primary chemical compounds found within organisms are carbohydrates, proteins, fats and vitamins.
> Lithosphere: oxygen, silicon, aluminium, iron, calcium. Natural mixtures include rocks, ores, sands, coal, oil, natural gas, soil.
> Hydrosphere: oxygen, hydrogen, chlorine, sodium, magnesium. Salt water, permafrost, underground, rivers, lakes, reservoirs.
> Atmosphere: nitrogen, oxygen, argon, hydrogen, carbon. Carbon dioxide, water vapour etc.
> The composition of the Earth is constant. The earth is, materially, a closed system: matter is not lost or gained.
1.4 Identify and describe procedures that can be used to separate naturally occurring mixtures
1.5 Assess separation techniques for their suitability in separating examples of earth’s materials, identifying the differences in properties which enable these separations
Separation technique(s)
Component of mixture
Example
Property used
Filtering and decanting
Solids and liquids
Sediment from wine
Solubility
Sieving
Solids of different sizes
Flour and wheat germ
Particle size
Magnetic Separation
Magnetic and non-magnetic solids
Sand and iron
Magnetic attraction
Solvation, filtration and evaporation
Insoluble and soluble solids
Sand and salt
Solubility
Evaporation, crystallisation and distillation
Dissolved solids in liquids
Salts and fresh water from sea water
Boiling point
Fractional distillation
Liquids with different boiling points
Petroleum fractions from crude oil
Boiling point
Liquefaction and fractional distillation
Gases with different boiling points
Nitrogen and oxygen from air
Boiling point
Separating funnel
Liquids that do not mix with different densities
Oil and water
Solubility and density
1.6 Describe situations in which gravimetric analysis supplies useful data for chemists and other scientists
> Gravimetric analysis: the amounts of substance present in a mixture or compound are determined by mass
> Gravimetric analysis is a quantitative analysis as it determines relative amounts of components in a mixture or compound
> Gravimetric analysis is a qualitative analysis in the sense that it identifies the substances present in the composition of the mixture or compound
> Examples of gravimetric analysis include:
1.8 Identify IUPAC names for carbon compounds as they are encountered.
Code
No. Carbons
Meth
1
Eth
2
Prop
3
But
4
Pent
5
Hex
6
Hept
7
Oct
8
Non
9
Dec
10
an = only carbon-carbon single bonds
en = contains at least one carbon-carbon double bond
2.1 Explain the relationship between the reactivity of an element and the likelihood of its exiting as an uncombined element
> The more reactive an element, the more likely it is to be found combined as a compound e.g. sodium as salt (sodium chloride)
> The less reactive an element, the more likely it is to be found uncombined as an element e.g. gold, silver, noble gases
> Some elements occur both as uncombined elements and as combined e.g. oxygen as a gaseous element in air and oxygen combined with hydrogen to form water
2.2 Classify elements as metals, non-metals and semi-metals according to their physical properties
Property
Metals
Non-metals
Metalloids
Melting point
Usually high
Usually low
High
Boiling point
Usually high
Usually low
Usually high
Electrical conductivity
High
Very low
Low
Thermal conductivity
High
Very low
Low
Appearance
Shiny
Usually not shiny
Variable
Hardness
Usually hard
N/A (gases, liquids), solids usually soft
N/A (gases, liquids), usually relatively soft solids
Malleability/ ductility
Usually malleable and ductile
Not malleable nor ductile, often brittle
Variable
Physical State
Often solid, occasional liquid (mercury)
Variable, usually gaseous
Variable
Examples
Lead, iron, magnesium, gold
Oxygen, helium, argon, carbon
Silicon, arsenic
2.3 Account for the uses of metals and non-metals in terms of their physical properties.
Element
Use
Relevant Physical Property
Gold
Jewellery
Lustrous, workable
Silver
Jewellery
Lustrous, workable
Iron
Making steel for buildings
Mechanical strength
Aluminium
Window frames
Light
Nitrogen
Burning off warts
Very low boiling point
Helium
Balloons
Low density
Carbon
Diamonds
Reflects and refracts light
Carbon
Graphite pencils
Makes marks on paper
Copper
Electrical wiring
High electrical conductivity
3.1 Identify that matter of particles that are continuously moving and interacting
> All matter is made of particles continuously in motion and interacting with each other: this is the kinetic particle theory.
> The energy of the particles controls their movement.
> Solids: particles are close together vibrating in fixed positions
> Liquids: particles are close together and moving more freely
> Gases: particles are far apart and moving very freely
3.2 Describe qualitatively the energy levels of electrons in atoms
Energy Level
Maximum number of electrons
K
2
L
8
M
18
N
32
3.3 Describe atoms in terms of mass and atomic number
> Mass number = the number of protons + the number of neutrons
> Atomic number = the number of protons
> Number of neutrons = mass number – atomic number
3.4 Describe the formation of ions of atoms gaining or losing electrons
3.7 Describe the formation of ionic compounds in terms of attraction of ions of opposite charges
> An atom forms a positive ion when it loses an electron
> An atom forms a negative ion when it gains an electron
> The charge of an atom is x+ where electrons are lost and x is the number of electrons lost (by convention you don’t write 1+, just +)
> The charge of atom is x- where electrons are gained and x is the number of electrons gained
> Monatomic ions: ions formed from one element e.g. Mg2+ = magnesium ion
> Polyatomic ions: ions formed from compounds e.g. OH- = hydroxide ion
> Opposite charged ions attract to each other forming ionic compounds; e.g. In MgO,
2+ Mg ions are attracted to 2- oxide ions forming a stable Magnesium Oxide compound that has no overall charge
3.5 Apply the Periodic Table to predict the ions atoms of metals and non-metals
> Metal atoms lose electrons so they form positive ions
· Group 1 metals lose 1 electron and form 1+ ions
· Group 2 metals lose 2 electrons and form 2+ ions
· Group 3 metals lose 3 electrons and form 3+ ions
> Non-metals gain electrons so they form negative ions
> The transition metals can form a different number of ions. It is impossible to predict the number of charge of the ions apart from the fact their ions will always be positive.
> Substances that form positive ions are called cations because they are attracted to the negative charge of the cathode.
> Substances that form negative ions are called anions because they are attracted to the positive cathode.
> Elements that lose electrons are said to be electropositive.
> Elements that gain electrons are said to be electronegative.
3.6 Apply Lewis electron dot structures to the formation of ions and the electron sharing in some simple molecules
> A Lewis electron dot structure uses dots to show the number of electrons in the outer shell of an atom only
> Lewis electron dot diagrams can be used to show the sharing of electrons within molecules. The electrons that are shared are drawn side by side, or they can be shown by drawing a circle around them. By sharing electrons, each atom in the molecule has a full shell of electrons. Thus, the arrangement forms stable structures.
> Some compounds occur as molecules forming covalent bonds. The covalent bond is often shown by drawing a circle around the pair of bonding electrons.
3.8 Describe molecules as particles which can move independently of each other
3.9 Distinguish between molecules containing one atom (the noble gases) and molecules with more than one atom
> Molecule: the smallest unit of a substance that can move independently.
> Molecules made of one atom are said to be monatomic.
> Molecules made of more than one atom are said to be polyatomic. Molecules made of two atoms are said to be diatomic.
3.10 Describe the formation of covalent molecules in terms of sharing electrons
> The covalent bonds – sharing electrons. When two non-metal atoms react together, both of them need to gain electrons to achieve complete shells. To achieve this, the two atoms share electrons forming covalent bonds.
> E.g. hydrogen – contains one electron. Its shell needs two electrons to be complete. When two hydrogen atoms get close enough, their shells overlap. They share their single electrons, now both atoms have 2 electrons and are stable.
3.11 Construct formulae for compounds formed from ions and atoms sharing electrons
> For a metal: [M (g)] à (M+) + (e-) --- endothermic (absorbs heat)
> For a non-metal: [X (g)] + (e-) à (X-) --- exothermic (produces heat)
4.1 Identify the differences physical and chemical change in terms of rearrangement of particles
> Physical changes are changes in physical properties and do not change the composition of the particles
> Chemical changes are chemical reactions; new substances are formed. Chemical changes form substances with different compositions and properties
4.2 Summarise the difference between the boiling of water and electrolysis of water as an example of the differences between physical and chemical change
> Boiling water is a physical change – the physical state of water is modified from liquid to gas
> Electrolysing water is a chemical change – it is a chemical reaction whereby water decomposes to form gaseous hydrogen and oxygen
Chemical Processes
Physical Processes
At least one new substance is formed
No new substances are formed
Difficult to reverse
Easily reversed by adding or subtracting heat energy or separating/mixing
Usually a large amount of heat energy involved in the process
Usually a relatively small amount of heat energy involved in the process
4.3 Identify light, heat and electricity as the common forms of energy that may be released or absorbed during the decomposition or synthesis of substances and identify examples of these changes occurring in everyday life
Type of Energy
Industrial Example
Everyday Example
Heat
Decomposition of limestone to form lime
Decomposition of baking soda to form carbon dioxide in baking
Light
Decomposition of silver bromide in photographic paper
Production of sugars and oxygen during photosynthesis
Electrical
Production of aluminium through electrolysis
Synthesis of nitrogen oxide by lightning strikes
4.4 Explain the amount of energy needed to separate atoms in a compound is an indication of the strength of attraction, or bond, between them
> The stronger the forces of attraction holding the atoms in a compound together the more energy needed to break these bonds.
> For covalent bonds, usually between 150-1100 kJ/mol is needed.
> For ionic substances, around 400-4000 kJ/mol is needed.
> Bond energy: the energy involved in making or breaking bonds and is usually quoted in kJ per mole of the particular bond involved.
> The bond energy is an indication of the strength of attraction between atoms or ions.
5.1 Identify the differences between physical and chemical properties of elements, compounds and mixtures
> Each element and compound has its own distinct physical and chemical properties.
> E.g. sodium, chlorine and sodium chlorine each have very different properties (as in the table below).
Substance
Chemical Properties
Physical Properties (at 25*C)
Sodium chloride
Does not burn, no reaction with water and hydrogen
White crystals, soluble in water, does not conduct electricity as a solid, does conduct electricity as a liquid
Sodium
Burns in oxygen, violent reactions with water and hydrogen
Soft silvery metal, conducts heat and electricity as a solid/liquid
Chlorine
Burns in air, reaction with water, violent reaction with hydrogen
Green gas, does not conduct electricity at all
> The individual components (elements/compounds) of a mixture keep their own properties.
5.2 Describe the physical properties used to classify compounds as ionic, covalent molecular or covalent network
Physical Property
Ionic
Covalent molecular
Network covalent
Example
Sodium chloride (salt)
Water (H20)
Silicon Dioxide (sand)
Physical state
Solids
Variable
Solids
Appearance
Powder/crystals
Dull if solid
Shiny
Colour
Variable
Variable
Silvery
Odour
Odourless
Can have strong odour
Odourless
Density
Medium
Low to medium
Medium
Hardness
Hard/brittle
Varies, but generally soft
Hard/brittle
Structure
Crystalline
Shapeless
Crystalline
Solubility in H20
Some
Some slightly soluble
Insoluble
Electrical conductivity of solutions
Good
Bad
n/a
Electrical conductivity as a solid
Bad
Bad
Bad
Thermal conductivity
Poor
Poor
Good
Melting point
High
Generally low
High
5.3 Distinguish between metallic, ionic and covalent bonds
> Metallic: an electrostatic attraction between a metal cation (+) the sea of mobile electrons (-) surrounding it
> Ionic: bonds between metals (+) and non-metals (-)
> Covalent: bonds between two non-metals (share electrons)
5.4 Describe metals as three-dimensional lattices of ions in sea of electrons
> Metals are composed of cations (metal ions) arranged in a repeating, cubic pattern. The structure is crystalline.
> The strong metallic bonds are formed through the attraction of the cations to the outer arrangement of delocalised electrons. These electrons are mobile, being shared around by all ions in the lattice.
5.5 Describe ionic compounds in terms of repeating three-dimensional lattices of ions
> Ionic compounds are regular, crystalline structures created through the electrostatic attractions between oppositely charged ions
> The strong forces of attraction are due to very strong ionic bonds - with cations forming sturdy bonds with anions
5.6 Explain why the formula for an ionic compound is an empirical formula
> Empirical formula: the simplest whole number ratio of different atoms in a substance
> Since an ionic compound is a repeating structure of ions, the simplest ratio is useful when showing how the particles repeat to form the structure.
> E.g. MgCl2 shows that the ratio of Mg ions to chloride ions is 1:2 – there are really trillions of magnesium and chloride ions in the ionic compound but 1:2 shows the simplest ratio of atoms
5.7 Identify common elements that exist as molecules or as covalent lattices
> Molecules is the smallest particle of two or more atoms that retains the physical and chemical properties of that substances
> Diatomic elements: hydrogen, oxygen, nitrogen, fluorine, chlorine, bromine, iodine
> Polyatomic elements: phosphorus (P9), sulphur (S8)
> Tetrahedral (each atom bonded to four others) covalent lattices: carbon (diamond), silicon, germanium
> Hexagonal (each atom bonded to three others) covalent lattices: carbon (graphite), boron
5.8 Explain the relationship between the properties of conductivity and hardness and the structure of ionic, covalent molecular and covalent network structures
Bonding type
Physical property
Structure
Ionic
Poor electrical conductivity as solids
The ions are localised in the crystalline lattice due to the strong electrostatic bonds
Ionic
Electrical conductivity as a molten or dissolved
Ions are free to move, able to carry electrical impulses
Ionic
Hard, very brittle
The strong 3-D forces between ions resist compression and distortion (hard). When a force is applied to a small area of the crystal, the forces break and the crystal shears apart (brittle)
Covalent molecular
Poor electrical conductivity in all cases
No delocalised electrons nor ions capable of carrying an electrical current
Covalent molecular
Soft
Weak inter-molecular forces
Covalent Network
Poor electrical conductivity
All valence electrons are involved in bonding and thus, no electrons are available to carry a current
Covalent Network
Very hard, brittle
Short, strong covalent bonds in the close packed lattice structure, which makes it unable to bend or distort
UMAD
Chemistry Revision – Module 1 – Chemical Earth
1.1 Construct word and balanced formulae equations of chemical reactions as they are encountered
1.7 Apply systematic naming of inorganic compounds as they are encountered in the laboratory
> IDE = compounds composed of two elements only
> ATE = compounds that contain oxygen
> PER = compounds that contain extra atoms of one of the elements
> Method for writing a two element compound:
- Write the symbols of the elements that make up the compound
- Write the valency number of each element at the bottom, right hand side of each symbol
- Swap the valency numbers of the elements
- Divide the valency numbers by any common denominator (if applicable)
- Rewrite the formula omitting the number 1 (if applicable)
- Write the symbols of the element and the multi-atom compound present
- Put brackets around the multi-atom component
- Write the valencies of the element and the multi-atom component
- Cancel down to get the smallest whole number ratio
- Rewrite the formula omitting the number 1 (if applicable), and also omitting the brackets around the multi-element component if there is only 1 lot of it
- Write symbol of the reactants
- Write an arrow to show reactants turning into products
- Write in the formula of the product(s)
- Balance the equation, ensuring there are the same number of atoms of each element on each side of the equation
- Insert state symbols (s, l, g, aq)
- Hydroxide = OH (valency 1)
- Nitrate = NO3 (valency 1)
- Ammonium = NH4 (valency 1)
- Carbonate = CO3 (valency 2)
- Sulphate = SO4 (valency 2)
- Cyanide = CN (valency 1)
- Hydro-carbonate = HCO3 (valency 1)
- Hydrogen-sulphate = HSO4 (valency 1)
- Phosphate = PO4 (valency 3)
- Manganate = MnO4 (valency 1)
1.2 Identify the difference between elements, compounds and mixtures in terms of the particle theory
> Particle theory: The kinetic theory of matter (particle theory) says that all matter consists of many, very small particles which are constantly moving or in a continual state of motion.
> Element: a substance that cannot be broken down into a simpler substance.
> Compound: two or more elements chemically combined and that can be broken down into its simpler substances by chemical means
> Mixture: two or more substances NOT chemically combined and that can be broken down by physical means.
1.3 Identify that the biosphere, lithosphere, hydrosphere and atmosphere contain examples of mixtures of elements and compounds.
> Biosphere: oxygen, silicon, aluminium, iron, calcium. Living organisms are organic (carbon-based). Primary chemical compounds found within organisms are carbohydrates, proteins, fats and vitamins.
> Lithosphere: oxygen, silicon, aluminium, iron, calcium. Natural mixtures include rocks, ores, sands, coal, oil, natural gas, soil.
> Hydrosphere: oxygen, hydrogen, chlorine, sodium, magnesium. Salt water, permafrost, underground, rivers, lakes, reservoirs.
> Atmosphere: nitrogen, oxygen, argon, hydrogen, carbon. Carbon dioxide, water vapour etc.
> The composition of the Earth is constant. The earth is, materially, a closed system: matter is not lost or gained.
1.4 Identify and describe procedures that can be used to separate naturally occurring mixtures
1.5 Assess separation techniques for their suitability in separating examples of earth’s materials, identifying the differences in properties which enable these separations
Separation technique(s)
Component of mixture
Example
Property used
Filtering and decanting
Solids and liquids
Sediment from wine
Solubility
Sieving
Solids of different sizes
Flour and wheat germ
Particle size
Magnetic Separation
Magnetic and non-magnetic solids
Sand and iron
Magnetic attraction
Solvation, filtration and evaporation
Insoluble and soluble solids
Sand and salt
Solubility
Evaporation, crystallisation and distillation
Dissolved solids in liquids
Salts and fresh water from sea water
Boiling point
Fractional distillation
Liquids with different boiling points
Petroleum fractions from crude oil
Boiling point
Liquefaction and fractional distillation
Gases with different boiling points
Nitrogen and oxygen from air
Boiling point
Separating funnel
Liquids that do not mix with different densities
Oil and water
Solubility and density
1.6 Describe situations in which gravimetric analysis supplies useful data for chemists and other scientists
> Gravimetric analysis: the amounts of substance present in a mixture or compound are determined by mass
> Gravimetric analysis is a quantitative analysis as it determines relative amounts of components in a mixture or compound
> Gravimetric analysis is a qualitative analysis in the sense that it identifies the substances present in the composition of the mixture or compound
> Examples of gravimetric analysis include:
- Determining the amount of sand, salt and water in a sand/salt/water mixture (see practical sheet).
- Analysis of foodstuffs e.g. the moisture content of grain prior to sale, the amount of dissolved solids in mineral water.
- The chemical composition of medicines and drugs require strict specifications to ensure they are beneficial to health and not dangerous.
- The percentage of impurities in goods such as iron in bronze.
1.8 Identify IUPAC names for carbon compounds as they are encountered.
Code
No. Carbons
Meth
1
Eth
2
Prop
3
But
4
Pent
5
Hex
6
Hept
7
Oct
8
Non
9
Dec
10
an = only carbon-carbon single bonds
en = contains at least one carbon-carbon double bond
2.1 Explain the relationship between the reactivity of an element and the likelihood of its exiting as an uncombined element
> The more reactive an element, the more likely it is to be found combined as a compound e.g. sodium as salt (sodium chloride)
> The less reactive an element, the more likely it is to be found uncombined as an element e.g. gold, silver, noble gases
> Some elements occur both as uncombined elements and as combined e.g. oxygen as a gaseous element in air and oxygen combined with hydrogen to form water
2.2 Classify elements as metals, non-metals and semi-metals according to their physical properties
Property
Metals
Non-metals
Metalloids
Melting point
Usually high
Usually low
High
Boiling point
Usually high
Usually low
Usually high
Electrical conductivity
High
Very low
Low
Thermal conductivity
High
Very low
Low
Appearance
Shiny
Usually not shiny
Variable
Hardness
Usually hard
N/A (gases, liquids), solids usually soft
N/A (gases, liquids), usually relatively soft solids
Malleability/ ductility
Usually malleable and ductile
Not malleable nor ductile, often brittle
Variable
Physical State
Often solid, occasional liquid (mercury)
Variable, usually gaseous
Variable
Examples
Lead, iron, magnesium, gold
Oxygen, helium, argon, carbon
Silicon, arsenic
2.3 Account for the uses of metals and non-metals in terms of their physical properties.
Element
Use
Relevant Physical Property
Gold
Jewellery
Lustrous, workable
Silver
Jewellery
Lustrous, workable
Iron
Making steel for buildings
Mechanical strength
Aluminium
Window frames
Light
Nitrogen
Burning off warts
Very low boiling point
Helium
Balloons
Low density
Carbon
Diamonds
Reflects and refracts light
Carbon
Graphite pencils
Makes marks on paper
Copper
Electrical wiring
High electrical conductivity
3.1 Identify that matter of particles that are continuously moving and interacting
> All matter is made of particles continuously in motion and interacting with each other: this is the kinetic particle theory.
> The energy of the particles controls their movement.
> Solids: particles are close together vibrating in fixed positions
> Liquids: particles are close together and moving more freely
> Gases: particles are far apart and moving very freely
3.2 Describe qualitatively the energy levels of electrons in atoms
Energy Level
Maximum number of electrons
K
2
L
8
M
18
N
32
3.3 Describe atoms in terms of mass and atomic number
> Mass number = the number of protons + the number of neutrons
> Atomic number = the number of protons
> Number of neutrons = mass number – atomic number
3.4 Describe the formation of ions of atoms gaining or losing electrons
3.7 Describe the formation of ionic compounds in terms of attraction of ions of opposite charges
> An atom forms a positive ion when it loses an electron
> An atom forms a negative ion when it gains an electron
> The charge of an atom is x+ where electrons are lost and x is the number of electrons lost (by convention you don’t write 1+, just +)
> The charge of atom is x- where electrons are gained and x is the number of electrons gained
> Monatomic ions: ions formed from one element e.g. Mg2+ = magnesium ion
> Polyatomic ions: ions formed from compounds e.g. OH- = hydroxide ion
> Opposite charged ions attract to each other forming ionic compounds; e.g. In MgO,
2+ Mg ions are attracted to 2- oxide ions forming a stable Magnesium Oxide compound that has no overall charge
3.5 Apply the Periodic Table to predict the ions atoms of metals and non-metals
> Metal atoms lose electrons so they form positive ions
· Group 1 metals lose 1 electron and form 1+ ions
· Group 2 metals lose 2 electrons and form 2+ ions
· Group 3 metals lose 3 electrons and form 3+ ions
> Non-metals gain electrons so they form negative ions
- Group 5 non-metals gain 3 electrons and form 3- ions
- Group 6 non-metals gain 2 electrons and form 2- ions
- Group 7 non-metals gain 1 electrons and form 1- ions
> The transition metals can form a different number of ions. It is impossible to predict the number of charge of the ions apart from the fact their ions will always be positive.
> Substances that form positive ions are called cations because they are attracted to the negative charge of the cathode.
> Substances that form negative ions are called anions because they are attracted to the positive cathode.
> Elements that lose electrons are said to be electropositive.
> Elements that gain electrons are said to be electronegative.
3.6 Apply Lewis electron dot structures to the formation of ions and the electron sharing in some simple molecules
> A Lewis electron dot structure uses dots to show the number of electrons in the outer shell of an atom only
> Lewis electron dot diagrams can be used to show the sharing of electrons within molecules. The electrons that are shared are drawn side by side, or they can be shown by drawing a circle around them. By sharing electrons, each atom in the molecule has a full shell of electrons. Thus, the arrangement forms stable structures.
> Some compounds occur as molecules forming covalent bonds. The covalent bond is often shown by drawing a circle around the pair of bonding electrons.
3.8 Describe molecules as particles which can move independently of each other
3.9 Distinguish between molecules containing one atom (the noble gases) and molecules with more than one atom
> Molecule: the smallest unit of a substance that can move independently.
> Molecules made of one atom are said to be monatomic.
> Molecules made of more than one atom are said to be polyatomic. Molecules made of two atoms are said to be diatomic.
3.10 Describe the formation of covalent molecules in terms of sharing electrons
> The covalent bonds – sharing electrons. When two non-metal atoms react together, both of them need to gain electrons to achieve complete shells. To achieve this, the two atoms share electrons forming covalent bonds.
> E.g. hydrogen – contains one electron. Its shell needs two electrons to be complete. When two hydrogen atoms get close enough, their shells overlap. They share their single electrons, now both atoms have 2 electrons and are stable.
3.11 Construct formulae for compounds formed from ions and atoms sharing electrons
> For a metal: [M (g)] à (M+) + (e-) --- endothermic (absorbs heat)
> For a non-metal: [X (g)] + (e-) à (X-) --- exothermic (produces heat)
4.1 Identify the differences physical and chemical change in terms of rearrangement of particles
> Physical changes are changes in physical properties and do not change the composition of the particles
> Chemical changes are chemical reactions; new substances are formed. Chemical changes form substances with different compositions and properties
4.2 Summarise the difference between the boiling of water and electrolysis of water as an example of the differences between physical and chemical change
> Boiling water is a physical change – the physical state of water is modified from liquid to gas
> Electrolysing water is a chemical change – it is a chemical reaction whereby water decomposes to form gaseous hydrogen and oxygen
Chemical Processes
Physical Processes
At least one new substance is formed
No new substances are formed
Difficult to reverse
Easily reversed by adding or subtracting heat energy or separating/mixing
Usually a large amount of heat energy involved in the process
Usually a relatively small amount of heat energy involved in the process
4.3 Identify light, heat and electricity as the common forms of energy that may be released or absorbed during the decomposition or synthesis of substances and identify examples of these changes occurring in everyday life
Type of Energy
Industrial Example
Everyday Example
Heat
Decomposition of limestone to form lime
Decomposition of baking soda to form carbon dioxide in baking
Light
Decomposition of silver bromide in photographic paper
Production of sugars and oxygen during photosynthesis
Electrical
Production of aluminium through electrolysis
Synthesis of nitrogen oxide by lightning strikes
4.4 Explain the amount of energy needed to separate atoms in a compound is an indication of the strength of attraction, or bond, between them
> The stronger the forces of attraction holding the atoms in a compound together the more energy needed to break these bonds.
> For covalent bonds, usually between 150-1100 kJ/mol is needed.
> For ionic substances, around 400-4000 kJ/mol is needed.
> Bond energy: the energy involved in making or breaking bonds and is usually quoted in kJ per mole of the particular bond involved.
> The bond energy is an indication of the strength of attraction between atoms or ions.
5.1 Identify the differences between physical and chemical properties of elements, compounds and mixtures
> Each element and compound has its own distinct physical and chemical properties.
> E.g. sodium, chlorine and sodium chlorine each have very different properties (as in the table below).
Substance
Chemical Properties
Physical Properties (at 25*C)
Sodium chloride
Does not burn, no reaction with water and hydrogen
White crystals, soluble in water, does not conduct electricity as a solid, does conduct electricity as a liquid
Sodium
Burns in oxygen, violent reactions with water and hydrogen
Soft silvery metal, conducts heat and electricity as a solid/liquid
Chlorine
Burns in air, reaction with water, violent reaction with hydrogen
Green gas, does not conduct electricity at all
> The individual components (elements/compounds) of a mixture keep their own properties.
5.2 Describe the physical properties used to classify compounds as ionic, covalent molecular or covalent network
Physical Property
Ionic
Covalent molecular
Network covalent
Example
Sodium chloride (salt)
Water (H20)
Silicon Dioxide (sand)
Physical state
Solids
Variable
Solids
Appearance
Powder/crystals
Dull if solid
Shiny
Colour
Variable
Variable
Silvery
Odour
Odourless
Can have strong odour
Odourless
Density
Medium
Low to medium
Medium
Hardness
Hard/brittle
Varies, but generally soft
Hard/brittle
Structure
Crystalline
Shapeless
Crystalline
Solubility in H20
Some
Some slightly soluble
Insoluble
Electrical conductivity of solutions
Good
Bad
n/a
Electrical conductivity as a solid
Bad
Bad
Bad
Thermal conductivity
Poor
Poor
Good
Melting point
High
Generally low
High
5.3 Distinguish between metallic, ionic and covalent bonds
> Metallic: an electrostatic attraction between a metal cation (+) the sea of mobile electrons (-) surrounding it
> Ionic: bonds between metals (+) and non-metals (-)
> Covalent: bonds between two non-metals (share electrons)
5.4 Describe metals as three-dimensional lattices of ions in sea of electrons
> Metals are composed of cations (metal ions) arranged in a repeating, cubic pattern. The structure is crystalline.
> The strong metallic bonds are formed through the attraction of the cations to the outer arrangement of delocalised electrons. These electrons are mobile, being shared around by all ions in the lattice.
5.5 Describe ionic compounds in terms of repeating three-dimensional lattices of ions
> Ionic compounds are regular, crystalline structures created through the electrostatic attractions between oppositely charged ions
> The strong forces of attraction are due to very strong ionic bonds - with cations forming sturdy bonds with anions
5.6 Explain why the formula for an ionic compound is an empirical formula
> Empirical formula: the simplest whole number ratio of different atoms in a substance
> Since an ionic compound is a repeating structure of ions, the simplest ratio is useful when showing how the particles repeat to form the structure.
> E.g. MgCl2 shows that the ratio of Mg ions to chloride ions is 1:2 – there are really trillions of magnesium and chloride ions in the ionic compound but 1:2 shows the simplest ratio of atoms
5.7 Identify common elements that exist as molecules or as covalent lattices
> Molecules is the smallest particle of two or more atoms that retains the physical and chemical properties of that substances
> Diatomic elements: hydrogen, oxygen, nitrogen, fluorine, chlorine, bromine, iodine
> Polyatomic elements: phosphorus (P9), sulphur (S8)
> Tetrahedral (each atom bonded to four others) covalent lattices: carbon (diamond), silicon, germanium
> Hexagonal (each atom bonded to three others) covalent lattices: carbon (graphite), boron
5.8 Explain the relationship between the properties of conductivity and hardness and the structure of ionic, covalent molecular and covalent network structures
Bonding type
Physical property
Structure
Ionic
Poor electrical conductivity as solids
The ions are localised in the crystalline lattice due to the strong electrostatic bonds
Ionic
Electrical conductivity as a molten or dissolved
Ions are free to move, able to carry electrical impulses
Ionic
Hard, very brittle
The strong 3-D forces between ions resist compression and distortion (hard). When a force is applied to a small area of the crystal, the forces break and the crystal shears apart (brittle)
Covalent molecular
Poor electrical conductivity in all cases
No delocalised electrons nor ions capable of carrying an electrical current
Covalent molecular
Soft
Weak inter-molecular forces
Covalent Network
Poor electrical conductivity
All valence electrons are involved in bonding and thus, no electrons are available to carry a current
Covalent Network
Very hard, brittle
Short, strong covalent bonds in the close packed lattice structure, which makes it unable to bend or distort
UMAD
Sanical
SpiderAnderson
Wateva, I'm going to sleep. You might find it unusual that I've started my notes but so is half my grade so the only reason I'm doing it is just for the sake of keeping up. Seriously, state ranks don't come that easy.
oh and at @hayabusaboston: thanks for your support even if it was sarcastic. But I'm not aiming for a state rank in maths. 98+ in ex 1 and I'm happy.
oh and at @hayabusaboston: thanks for your support even if it was sarcastic. But I'm not aiming for a state rank in maths. 98+ in ex 1 and I'm happy.
Aerath
Retired
- Joined
- May 10, 2007
- Messages
- 10,169
- Gender
- Undisclosed
- HSC
- N/A
So like...what school do you go to?
You do know that a few of the BoSers in 2012 go to Top 5 schools as well, right?
Sanical
SpiderAnderson
Who said I didn't go to a top 5 school. The only reason I wouldn't say is because it's east to tell I'm a guy, so that leaves two schools left: baulkham and ruse. Don't know many ruse kids that would waste time here, esp in holidays so yeah.. Anyway, why does it matter what school I go to. Does it cause a confliction in what I've said?
Yeah, you should. I'd say just do first or maybe even second module for your subjects if you plan on making your 98+ aim easier.
hayabusaboston
Well-Known Member
For the sake of keeping up? I thought you went 2.5 modules ahead of everyone by your own initiative. I wasn't sarcastic man, I believe we can all get state ranks if we try hard enough
if you get 98 or more in ext 1 you'll get a state rank anyway. You're not doing ext 2 next year are you? My personal goal is to ensure that no james ruse kid beats me in any of my subjects. I don't mind people getting better than me, as long as it's not james ruse haha.
Sanical
SpiderAnderson
It was both to keep up and my own initiative. And yeah, I'm doing ex2 as well. Really don't have time studying it until after my hsc so yeah, I'm going to have to catch up.For the sake of keeping up? I thought you went 2.5 modules ahead of everyone by your own initiative. I wasn't sarcastic man, I believe we can all get state ranks if we try hard enough
My personal goal is to ensure that no james ruse kid beats me in any of my subjects. I don't mind people getting better than me, as long as it's not james ruse haha.
Trust me, lol, the median atar in james ruse a few years back was 99.3. Last year they had almost 50 state ranks. There's no way you're not gonna have a ruse kid beat you. EDIT: sorry if that sounded harsh. But they have all the state ranks pretty much =/. beating all of them is like coming first in all your subjects, lol
. Anyway, had to say this because as powlmao tells me, this will result in an ip ban if I try to demotivate you. I have no choice but to agree with you or that guy will keep unrepping and trying to ban me. @powlmao, couldn't care less if I had -5 reputation. I don't even know how it works so keep 'un'repping me for all i care.
Last edited:
Omnipotence
Kendrick Lamar
I lol'd - not true.
Sanical
SpiderAnderson
For the subjects he is doing, they do. If you disregard english, james ruse dominate top 5 in phys/chem/maths: http://www.boardofstudies.nsw.edu.au/ebos/static/TAINC_2010_12.html
Sanical
SpiderAnderson
I'm jealous that they are acing visual arts and sport. Sounds like you're schools great then. Since I'm not allowed to demotivate, according to you, I believe you'll get 99.95.
Actually it is the HSIE subjects.
slyhunter
Retired
- Joined
- May 17, 2009
- Messages
- 6,803
- Gender
- Male
- HSC
- 2011
You have one in Ancient History okay mate.
http://www.boardofstudies.nsw.edu.au/ebos/static/TAINC_2010_12.html
Creepy you know what school I go to.
slyhunter
Retired
- Joined
- May 17, 2009
- Messages
- 6,803
- Gender
- Male
- HSC
- 2011
What school do you go to again??
I know where Spiralflex goes and Sancial goes.
lol Sancial I actually know you, don't you realize?
hayabusaboston
Well-Known Member
Amigo, you see, you won't demotivate me, because
1. I am very much aware of Ruse being ahead of the state in the subjects i'm doing, that's precisely why I intend to kick their asses
2. as you say, beating them is like coming first in all your subjects, well my man, if that's what it takes to be ahead of every single ruse kid, then that's what im going to do
3. You don't know who I am, so you have no way of knowing that ruse kids will beat me, because you don't know my skill level in my subjects, so you can't assume immediately ruse kids are better.
4. You most definitely do not sound harsh
You sound more unfazed than anything else, that Ruse is unbeatable.5. I help myself with high goals, it maintains motivation and self esteem, helping me all the more.
So amigo, you must try it too
slyhunter
Retired
- Joined
- May 17, 2009
- Messages
- 6,803
- Gender
- Male
- HSC
- 2011
Hurlstone Ag, everyone here knows that.
Also you haven't accounted for the fact your school had 1 state ranking when you said it averages 5 a year lol.