Gladen T Maswera
Chemistry Unit 1: Introduction to Chemistry
Section A
1.1a) Gases don’t have fixed shapes because gas particles have little or no attraction to each other, hence they spread everywhere. The particles in a gas are very far apart and the forces between such widely spread particles are extremely weak. This means that gas particles will readily move away from each other. Their particles are not densely compacted. Whereas solids have a fixed shape because the atoms in them are bonded tightly together and there is little space between them.

1.1b) Solids, liquids and gases would not exist at such extreme temperatures because at a very high temperature higher than the maximum boiling point or melting point of either gas solid or liquid will cause a definite change of state, and thus they would not exist in their original form. The solid would melt, the liquid evaporate and the gas turns into plasma.
1.1c An atom is the basic unit of an element. An atom is a form of matter which may not be further broken down using any chemical means. A typical atom consists of protons neutrons and elements. A compound is the result of two or more elements becoming chemically combined together. The elements react chemically causing bonds to be formed between the atoms involved. An element is the simplest form of matter and cannot be decomposed into simpler substances. They are composed of one kind of atom each atom has the same properties and the same atomic number. Molecules are a result of two or more atoms being joined together chemically by a bond.
1.2(i) R would be suitable for filling a thermometer that records temperatures in Britain. (ii) P would be a liquid at room temperature because water boils at 100◦c and freeze at 0◦c and substance P is the one who’s temperatures are within this range. (iii) S and Q are most likely to be strong metals because of the very high melting and boiling points. (iv) Both Q and S would most likely to be ionically bonded because of the extremely high boiling and melting point. Ionic bonds have very high melting and boiling points because they are tighly bonded together. (v) Q and S would be solids at room temperature because of the high boiling and melting points. Solids have high melting and boiling points because the particles in them are highly compacted and are tightly bonded together.
1.3 Aim: To separate and compare a mixture of dyes in three differently coloured inks. Apparatus: Beaker, lid, chromatography paper, solvent, different colour dyes. Method: Pour a small amount of solvent such as ethanol into the beaker. Spot the chromatography paper with the three different colour dyes, about 1.0cm from the base of the paper. Suspend the paper into the beaker, making sure the level of the solvent is lower than that of the dye spots. Also make sure the paper doesn’t slide into the dye. Note the movement of the dye and separation of colours. Conclusion: Separated dyes.

2.1 Chlorine 35 Chlorine 37

2.2 The element Krypton is the one that cannot form a compound, because it has a full outer shell, therefore it does not need to give, take or share electrons.
2.3(a) Isotopes are atoms of the same element that have the same number of protons but different number of neutrons.

2.3(b) The average atomic mass = (64+65+68)÷3=65.6

3.1(a) Nitrogen (N2)

(b) We draw the electrons as dots and crosses to easily represent and differentiate between two valences of two or more elements.
Substance under test

Effects of gentle heat
Soluble in water
Solubility in Cyclohexane
Conduction on solids
Zinc Chloride
Melts
Yes
No
No
Potassium Iodine
Melts
Dissolved
No
No
Carbon Graphite
Changed colour to red
Mixed
No
Yes
Glucose (C6 H12O6)
Melted
Dissolved
No
No
Copper (Cu)
Turned red
No
No
Yes
Lead (Pb)
Melted & turned red
No
No
Yes
Silicon Dioxide (Si02)
No change
No
No
No

We concluded that ionic bonds conduct electricity and have high melting and