IV) Chemical compounds

A) Compound: substance formed of the atoms of two or more elements

1) Properties of a compound are different from the atoms that make it up

a) Example: water H₂0 - two gases combine to make a liquid

b) Example Sugar is made of two gases and a solid: hydrogen and oxygen, as well as carbon, which is what makes up diamonds and coal

2) Chemical Formula is the symbols of the elements that makeup a compound and how many atoms of each

a) H₂0 2 Hydrogen and 1 Oxygen

b) Salt: NaCl 1Sodium and 1 Chlorine

3) Ionic Bonds are caused by the attraction between positive and negative ions.

a) Salt – Sodium atoms lose an electron to Chlorine atoms, creating Positive Sodium ions and Negative Chlorine atoms.

i) The opposite charge of the ions creates an attraction between them which causes them to bond together, creating salt

a) Chemical reaction can also form compound example Rust

b) Rust is formed by a chemical reaction between Iron ions and oxygen ions.

c) Metals combined with oxygen are called oxides

4) Covalent Bonds occur when two or more atoms share one or more electrons.

a) Water - 2 Hydrogen atoms share their one electron with 1 Oxygen atom, while the Oxygen atom shares one electron with each of the Hydrogen atoms

i) This fills the outer electron orbit of all three atoms.

B) Acids and Bases

1) Acids: are compounds that react easily with other substances and turn blue litmus paper red. They have a pH between 0 and 7

a) Acids diluted with water taste sour (Can be poisonous do not drink)

b) Acids are corrosive. Strong acids are very corrosive.

c) Oranges, Lemons and limes contain citric acid (weak acid) and are called citrus fruit.

d) Apples contain malic acid (also a weak acid)

2) Bases: are compounds that also react easily with other substances but turn red litmus blue. They have a pH between 7 and 14

a) Often feel slippery and have a bitter taste (Do Not Eat)

b) Strong bases are as destructive as strong acids

Corrosive Acids and Bases

3) A Neutral compound with a ph of 7. It is neither an acid or a base.

4) Acids and Bases are opposites and can neutralize each other

C) Uses of Acids and Bases

1) Acids

a) Human digestive system uses Hydrochloric acid produced by the stomach

b) Acids are also used to manufacture fertilizers, explosives

C) Acids used in the production of dyes for cotton and silk by making the dye resistance to fading from light and washing

2) Bases

a) Bases used in making soaps and cleaners

b) Also important part of cement

c) Also in paper making and petroleum