O-Level Chemistry Flashcards

Flashcards for O-Level Chemistry (Chapters 4-7.2)

Types of Bonding

Ionic bonding and covalent bonding.

Ionic Bonding

The electrostatic attraction between positively and negatively charged ions, formed by transfer of electrons from metal to non-metal.

Covalent Bonding

The electrostatic attraction between nuclei and the shared pair(s) of electrons between two non-metal atoms.

Properties of Ionic Compounds

High melting/boiling points, conduct electricity when molten or in aqueous solution, usually soluble in water.

Properties of Simple Covalent Substances

Low melting/boiling points, do not conduct electricity, usually insoluble in water.

Giant Covalent Structures

Large networks of covalently bonded atoms, e.g. diamond and graphite.

Why Graphite Conducts Electricity

It has delocalised electrons that can move between layers.

Why Diamond Doesn't Conduct Electricity

All electrons are used in bonding and there are no free electrons.

What Determines Physical Properties

The type of bonding and structure (ionic, covalent, metallic, simple molecular, giant covalent).

Metallic Bond

The electrostatic attraction between a lattice of positive metal ions and a sea of delocalised electrons.

Why Metals Conduct Electricity

They have delocalised electrons that can move freely to carry charge.

Why Alloys Are Harder Than Pure Metals

Different sized atoms distort the layers, making it harder for them to slide over each other.

Chemical Formula

A representation of a substance using element symbols and subscripts to show the ratio of atoms.

Chemical Equation

A representation of a chemical reaction using symbols and formulae.

Balanced Chemical Equation

An equation where the number of atoms of each element is the same on both sides.

State Symbols in Equations

s (solid), l (liquid), g (gas), aq (aqueous – dissolved in water).

Mole

The amount of substance that contains 6.022 × 10²³ particles (Avogadro’s number).

Molar Mass

The mass of one mole of a substance, in g/mol.

Formula: Moles from Mass

moles = mass / molar mass

Formula: Mass from Moles

mass = moles × molar mass

Formula: Moles from Gas Volume (at r.t.p.)

moles = volume / 24 dm³

Percentage by Mass Formula

percentage by mass = (Ar of element × number of atoms / Mr of compound) × 100%

Stoichiometry

The calculation of reactants and products in chemical reactions based on balanced equations.