GCSE AQA CHEMISTRY 🧪👩‍🔬💗

Ion

An atom or group of atoms with positive or negative charge

Metal

A shiny element which is often a good conductor of heat and electricity- they form basic oxides

Non-metal

Not conductive, forms acidic oxides

Metal atoms ____ electrons from their outer shell when forming ions

Lose

Why are metal ions positively charged?

They have more protons than electrons

Metal ions have the same electronic structure as

Noble gases (full outer shell, stable)

A sodium atom has formed an ion, whats its charge?

Positive

Non metals ____ electrons when forming ions

Gain

Non metal ions are negative because there are

More electrons than protons

Do non metal ions also share the same structure as a noble gas?

Yes

When do positive and negative ions form?

When a metal and non metal react

What causes the bonds in ionic bonds?

The oppositely charged ions are strongly attracted to eachother

Ionic bonds

Forms between two atoms when an electron is transferred from one atom to another, forming a positive-negative ion pair

Ionic lattice

The regular arrangement of ions in an ionic substance

What state are ionic compounds at room temperature

Solid

Ionic compounds have ____ melting and boiling points

High 👋

What causes the high melting and boiling points in ionic bonds?

The strong electrostatic forces of attraction between the oppositely charged ions

Electrostatic forces

The forces of attraction between oppositely charged particles

What allows a substance to conduct electricity?

-containing charged particles

-the particles are free to move

If an ionic compound is melted or aqueous (dissolved in water) it can…

Conduct electricity

When solid, ionic compounds are

Insulators

The actual masses of atoms, molecules and ions are measured in

Moles (mol)

Avogadro’s constant

The number of particles in one mole of particles- 6.02×10²³

Formula for calculating the number of particles

Avogadro’s constant (6.02×10²³) x amount of substance in mol

Formula for calculating mass

Relative formula mass x amount (in moles)

Formula for calculating the amount of a substance

Mass

---

relative atomic or formula mass

What is amount measured in?

Mol

Relative atomic mass applies to

Elements

Relative formula mass applies to

Compounds

Concentration

How much of a substance is dissolved in water

Concentration is measured in…

Mol/dm³

Solute

The dissolved substance in a solution

Concentration formula

Concentration in mol/dm³= amount of solute (mol)/ volume in dm³

How do we convert from cm³ to dm³

➗ 1000

How do we convert from dm³ to cm³

✖ 1000

What is the aim of a titration

They are used to find out how much acid is needed to neutralise an alkali

Apparatus needed for a titration experiment

• pipette

• Burette

• Conical flask

• Safety pipette filler

Pipette

A piece of apparatus used to measure accurate and repeatable volumes of liquid

Burette

A piece of apparatus used to add varying but measured volumes of solution during a titration

Simple molecules have ____ covalent bonds but ____ forces of attraction

Strong, weak

The three giant covalent structures

Diamond, graphite, silicon dioxide

Structure of diamond

Each carbon atoms forms four covalent bonds in a very rigid giant covalent structure

Structure of graphite

Each carbon atom forms three covalent bonds to create layers of hexagons.Each carbon atom also has one delocalised (free electron)

Structure of silicon dioxide

What sand is made of, one giant structure of silicon and oxygen

Allotropes

Different structural forms of the same element in the same physical state

Fullerenes

Molecules of carbon shaped like closed tubes or hollow balls

Example of a fullerene

Buckminister fullerene- it is a hollow sphere

Qualities of diamond

-strong covalent bonds = high mp

-no free electrons, doesn’t conduct

Metallic bonding involves

De localised electrons

Metallic bonds properties

-solid at room temp

-high mp & bp

Why are metals malleable?

The layers of atoms can slide over eachother

Why do we need alloys?

Pure metals are often too soft