basic principles of acids and bases (1 Viewer)

[jenez]

I am having trouble understanding the basic principles of our acids and bases topic during science and was wondering if anyone had a brief overview/ or could post any notes concerning, acids, bases, the periodic table, mixtures, substances, etc ( if not are there any reliable websites that provide brief overviews of this topic?) It would be greatly appreciated. Hoping to hear from you, Jen.

 

[~shinigami~]

Is there anyting in particular that you have trouble with?

Because there are numerous things that can be said about the above tings you've listed.

I'll be happy to answer any questions but my knowledge is very limited.

 

[kazan]

I am having trouble understanding the basic principles of our acids and bases topic during science and was wondering if anyone had a brief overview/ or could post any notes concerning, acids, bases, the periodic table, mixtures, substances, etc ( if not are there any reliable websites that provide brief overviews of this topic?) It would be greatly appreciated. Hoping to hear from you, Jen.

acids and bases can be described in differnt ways

bronsted lowry acid and base definition is currently thought to be the most correct

an acid is a proton donor,
a base is a proton acceptor.

this means that protons(hydrogen ions) will be displaced from acids and will be accpeted by bases

a good example is

HCL + H20 --> Cl + H30
acid base

the acid loses a hydrogen ion, and the base gains one
so that hydrochloric acid and water form, chlorine ions and hydronium ions



thats really basic

mixtures are discussed in the prelim

its 2 or more substances in an unfixed ratio

a compound is 2 or more substances in a fixed ratio

i just looked and read that you do ur hsc in 08, that makes u year 10?
i cant remember that stuff, so maybe all that was a waste

 

[~shinigami~]

About the periodic table: The number at the top is usually the atomic number which signifies the number of protons and electrons an element has and the number at the bottom is the atomic weight which signifies the number of protons + neutrons so if you minus the atomic number from the atomic weight, you'll get the number of neutrons.

Example: Carbon has the atomic number of 6 which means it has 6 protons in it's nucleus and 6 electrons orbiting around. Carbon also has an atomic weight of 12 which is the total of protons plus neutrons so just minus the atomic number i.e 12 - 6 = 6. Therefore there are 6 neutrons in the nucleus.

About elements joining to become compounds: So for the 1st 20 elements, it's quite simple. Each element has electrons orbiting the nucleus in "shells". The 1st shell can hold 2 electrons and the rest can hold 8 each. An element wants to be stable like the noble gases at the far right hand side, to do this they must have 8 electrons in the outer most shell (the valence shell). So elements that do not have full valence shells like to join together as compounds in either Ionic or Covalent bonds in order to achieve stability.

Example: Carbon has 6 electrons which means 2 electrons in the 1st shell and 4 in the next shell but Carbon wants to be stable so it must somehow gain or lose 4 electrons to have a full valence shell so it can join with other elements such as Hydrogen which has only one outer valence electron. 4 Hydrogens (with 1 valence electron each) can join with 1 Carbon to become CH₄ (Methane, the stuff that comes out of cow's arses). I think I've made it too complicated but I'm too relaxed to write anything coherent.

 

[falcon07]

Identification:
Acids usually have a proton (hydrogen ion) to donate, eg. HCl -> H+ + Cl-
Bases usually have a hydroxide, eg. NaOH -> Na+ + OH-
All acids and bases are in solution with water. Eg. hydrochloric acid is H+ and Cl- ions in solution and sodium hydroxide is Na+ and OH- ions in solution.

General acid equations:

Acid + Base -> Salt + Water
Acid + Metal -> Salt + Hydrogen
Acid + Carbonate -> Salt + water + carbon dioxide

In the acid + base reaction, the hydrogen ion bonds with the hydroxide ion to form water. Remaining in solution are chloride and sodium ions (a dissolved salt).
In the acid + metal reaction, H+ ions steal electrons from the metal and bond to form H2 (hydrogen gas). Remaining are positive metal ions and negative non-metal ions (a dissolved salt). Eg. Mg + 2HCl -> H2 + MgCl2
In the acid + carbonate reaction, hydrogen ions from the acid bond with oxygens from the carbonate to produce water, liberating CO2 gas. Remaining in solution are the salt ions, eg. CaCO3 + 2HCl -> H2O CO2 + CaCl2

Hope that makes sense.

 

[jenez]

Thank you ALL for all your help, you have been very helpful, I really appreciate it. =D, Jen