Chemistry part one

What is an Atom?

The smallest constituent unit of an element that retains its chemical properties.

Relative charge of a proton

$$+1$$

Relative charge of an electron

$$-1$$

Relative charge of a neutron

$$0$$

Location of protons and neutrons within an atom

Nucleus

Location of electrons within an atom

Energy shells surrounding the nucleus

What is the Atomic number

The total number of protons found in the nucleus.

Formula to calculate the number of neutrons

$$\text{Mass number} - \text{atomic number}$$

Relationship between protons and electrons in a neutral atom

They are equal in number.

What is an Isotope

Forms of an element that possess the same number of protons but differing numbers of neutrons.

Ionic bonding

Electrostatic attraction between oppositely charged ions.

Mechanism of ionic bonding

Electrons are transferred from metal atoms to non-metal atoms.

Covalent bonding

Electrostatic attraction formed by the sharing of pairs of electrons between atoms.

Metallic bonding

Electrostatic attraction between positive metal ions and delocalised electrons.

Elements that form ionic bonds

Metals and non-metals.

Elements that form covalent bonds

Non-metals.

Reason ionic compounds have high melting points

Strong electrostatic attractions between oppositely charged ions require large amounts of energy to overcome.

Reason ionic compounds conduct electricity when molten

The ions are free to move and carry electrical charge.

Reason metals conduct electricity

They have delocalised electrons that are free to move throughout the metallic lattice.

What is an Acid

A substance with a pH below $7$.

What is an Alkali

A soluble base with a pH above $7$.

Word equation for neutralisation

$$\text{Acid} + \text{base} \rightarrow \text{salt} + \text{water}$$

Reaction products: Acid + metal

$$\text{Salt} + \text{hydrogen}$$

Reaction products: Acid + carbonate

$$\text{Salt} + \text{water} + \text{carbon dioxide}$$

Chemical test for hydrogen gas

A lit splint held near the gas produces a squeaky pop sound.

Chemical test for oxygen gas

A glowing splint inserted into the gas relights.

Chemical test for carbon dioxide gas

Bubbling the gas through limewater turns the solution cloudy.

Oxidation (definition)

Gain of oxygen or loss of electrons.

Reduction (definition)

Loss of oxygen or gain of electrons.

What is Electrolysis

The breakdown of an ionic substance using electricity.

What is an Electrolyte

A liquid or solution containing mobile ions that conducts electricity.

Cathode

The negatively charged electrode.

Anode

The positively charged electrode.

Electrode reaction at the cathode

Positive ions gain electrons (reduction).

Electrode reaction at the anode

Negative ions lose electrons (oxidation).

Purpose of cryolite in aluminium extraction

Lowers the melting point of aluminium oxide.

Reason aluminium is extracted using electrolysis

Aluminium is more reactive than carbon.

Industrial extraction of iron

Reduction using carbon monoxide in a blast furnace.

Purpose of limestone in iron extraction

Removes acidic impurities by reacting to form slag.