Comparing Lithium, Sodium, Caesium And

Lithium,Sodium,Potassium,Rubidium,Caesium and Francium are all part of group 1.They are metals that can be easily cut.After being cut,it is shiny but it quickly tarnishes due to the fact that the metal reacts quickly with oxygen or water.The shiny surfaces of Sodium quickly tarnishes more quickly than Lithium and Potassium more tarnishes more quickly than Lithium.This shows that the reactivity increases as we move down the group.

Figure 1

Elements Melting point Boiling point Thermal Conductivity Electrical Conductivity

Lithium 182 1342 85 W/(m k) 1.1 *107 S/m

Sodium 100 882.8 140 W/(m k) 2.1 * 107 S/m

Potassium 63 758.8 100 W/(m k) 1.4 *107 S/m

Rubidium 41 688 58W/(m k) 8.3
*107 S/m

Caesium 30 670.8 36W/(m k) 5*107 S/m

Francium 27 676.8 N/A N/A

Generally,as we go down the group the melting point and boiling point decrease apart from Francium which is an outlier.Since group 1 is the alkali metals,this means that there are able to conduct heat well and are also able to conduct electricity also very well as they are able to lose an electron and generate electricity very well.
The trend with the thermal conductivity is that Lithium increase up till Sodium where after the thermal conductivity starts to decrease.There does not seem to be a clear cut trend with electrical conductivity.Lithium electrical conductivity is lower than Sodium but Sodium electrical conductivity is higher than Potassium.Rubidium electrical conductivity is higher than both Potassium and
Caesium.

This is what happens when a alkali metal reacts with water.This is because of the fact that the group 1 metals react vigorously with water.This makes an metal hydroxide plus hydrogen.

Alkali metal + water →alkali metal hydroxide + hydrogen

Fluorine,Chlorine,Bromine,Iodine and Astatine are all part of group 7 also know as the halogens.These elements are all non-metal which means they are unable to conduct electricity.But the trend in reactivity in this group is the opposite.The halogens get less reactive as we go down the group meaning Fluorine is more reactive than Chlorine.

Elements Melting point Boiling point

Fluorine -219.6 -188.12

Chlorine -101.5 -34.04

Bromine -7.3 59

Iodine 113.7 184.3

Astatine 302 336.8

The halogens melting point increases as we go down the group.The boiling point increases as we go down the group.This trend is the complete opposite trend that we have in group 1.
Chlorine is more reactive than bromine.This mean that chlorine can displace bromine in the compound sodium bromide and make sodium chloride plus bromine.Another example is that fluorine can displace chlorine.This is how the halogens can displace each other

chlorine + sodium bromide → sodium chloride + bromine

Task 2

There are two types of bonding.Covalent bonding and ionic bonding.

Ionic bonding occurs from positively ions and negatively ions,which attracts each other and bind together to form ionic compounds.Each ion is surrounded by an oppositely charged ion held by electrostatic attraction.

There are several way in which atoms can chemically form to create compounds.There are two different ions:

Metal ions

In some circumstances,metal atoms may lose electrons.This makes the atoms have more electrons than protons making a positive ion.

Non-metal ions

In some circumstances,Non-metal atoms may gain electrons.This makes the atoms have more electrons than protons making a negative
ion.

The formation of ionic bonding is usually shown in dots and cross model.

Covalent bonding is formed between non metals atoms, which combine together by sharing electrons.Covalent compounds have no free electrons and no ions meaning they can’t conduct electricity excluding graphite.Covalent bonding is formed usually in liquid and gas form.

Giant ionic bonding is arranged in a regular way to form giant ionic lattice.Lattices can be in either a regular small bonding or a giant bonding.In order to make giant bonding the arrangement must be repeated many times with large numbers of ions.This causes them to have high boiling points and melting points because it would be harder to break the strong intermolecular forces.They are not able to conduct electricity in solid state but can conduct in dissolved state in water.This is because when in a solid state the ions are in a fixed position and therefore are unable to move freely.But in liquid state,they are able to move freely in their liquid state.

Giant covalent bonding contains lots of non metals atoms.The atoms bond together to create giant covalent structures.Giant covalent structures also have very high boiling points and very high melting point, because a lot of strong intermolecular forces must be broken meaning lots of energy (heat energy) must be used to break the intermolecular forces.Giant covalent bonding have varied conductivity.This means only some can conduct electricity.Diamond is unable to generate electricity but graphite is able to generate electricity.Silicon are sem-conductive meaning they are non-conductive and conductive.