The Periodic Table (AQA GCSE Chemistry)

False.

Mendeleev arranged elements by both atomic mass and chemical properties.

The gaps in Mendeleev's table represented undiscovered elements.

Elements in the modern periodic table are arranged by increasing atomic number.

Before the discovery of protons, neutrons and electrons the early Periodic Table was ordered by atomic weight.

True.

Mendeleev organised the elements into vertical columns based on their properties and the properties of their compounds.

Mendeleev's theories about his Periodic Table were confirmed when these elements were later discovered and found to fit in his pattern.

The arrangement changed by ordering by atomic number rather than atomic mass.

True.

Non-metals are poor conductors of heat and electricity.

True.

Most elements are metals.

In terms of their physical state at room temperature, metals are typically solid and non-metals can be gases or solids.

Mercury and bromine are exceptions as they are liquid at room temperature.

Properties that are used to classify elements as metals or non-metals include:

• Conductivity.

• Melting / boiling point.

• Reaction with acid.

• Type of oxide formed.

False.

Non-metals are typically brittle, while metals are typically malleable and ductile.

Non-metals are generally located on the right-hand side of the Periodic Table.

Metals normally form basic oxides.

Non-metals generally have low melting and boiling points.

False.

Non-metals do not generally react with acids.

Metals typically have high electrical conductivity, are malleable / ductile, react with acids and form basic oxides.

Non-metals typically have lower electrical conductivity, are brittle, do not react with acids and form acidic oxides.

Group 0 of the Periodic Table is the noble gases.

Noble gases are unreactive as they have full outer shells of electrons.

False.

The Group 0 elements are all non-metal, monatomic, colourless, non-flammable gases at room temperature.

The electronic configuration of neon is 2.8.

True.

Noble gases are inert (unreactive).

Group 1 is called the alkali metals.

The two products formed when sodium reacts with water are sodium hydroxide and hydrogen.

Properties of Group 1 metals are:

• They are soft

• They have relatively low densities

• They have relatively low melting points

• They are very reactive

The alkali metals share similar chemical properties because they all have one electron / the same number of electrons in their outer shell.

The word equation for the reaction between lithium and water is:

lithium + water lithium hydroxide + hydrogen

The balanced symbol equation for the reaction between potassium and water is:

2K (s) + 2H₂O (l) ⟶ 2KOH (aq) + H₂ (g)

The product formed when sodium reacts with oxygen is sodium oxide.

Going down Group 1, reactivity increases.

The electronic configuration of potassium is 2.8.8.1.

Two other observations that would be made when sodium is added to water are:

• Floating

• Moving

• Melting / turning into a ball / sphere

• Getting smaller / disappearing / dissolving

• Leaving a white trail

The symbol equation for the reaction between chlorine and potassium is:

2K (s) + Cl₂ (g) → 2KCl (s)

True.

The reactions of the alkali metals with water get more vigorous as you descend the group.

The charge of the ions formed when a Group 1 metal loses an electron is 1+.

False.

Less energy is required to overcome the force of attraction as it gets weaker, so the outer electron is lost more easily as you descend the Group 1 metals.

Group 7 of the Periodic Table is the called the halogens.

Fluorine is in Group 7 of the Periodic Table because it has 7 electrons in its outer shell.

The colour and state of chlorine at room temperature is a pale green gas.

Going down the group, the melting point of the halogens increases.

A halogen displacement reaction is one where a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.

The word equation for the displacement reaction between potassium bromide and chlorine is:

potassium bromide + chlorine → potassium chloride + bromine

The balanced symbol equation for the reaction between potassium iodide and bromine is:

Br₂ + 2KI → 2KBr + I₂

Iodine cannot displace chlorine from potassium chloride because iodine is less reactive than chlorine.

Chlorine has a higher melting point than fluorine because there are stronger intermolecular forces which need more energy to overcome.

The charge of the ion formed when a halogen reacts with a Group 1 metals is 1-.

The trend in reactivity of the halogens is that going down the halogen, reactivity decreases.

Fluorine is the most reactive halogen because it has the fewest shells so it is easier for the nucleus to attract an electron.

False.

It becomes harder for halogen atoms to gain electrons as you go down the group making them less reactive.

Reactivity decreases going down Group 7 because the atoms have more shells. This means that there is a less attraction between an incoming electron and the positive nucleus, which makes it harder to gain an electron.

Hydrogen bromide is formed when hydrogen and bromine react together.