SACE Stage 1 Chemistry Practice Flashcards

Vocabulary-style flashcards covering the core concepts of SACE Stage 1 Chemistry including atomic structure, bonding, quantities, and energy.

Atomic Number

The number of protons in the nucleus of an atom; in a neutral atom, it is also equal to the number of electrons.

Mass Number

The total number of protons plus neutrons in an atom's nucleus.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers.

Relative Atomic Mass ($A_r$)

A weighted average of the masses of the naturally occurring isotopes of an element.

Electronegativity

The ability of an atom to attract bonding electrons; it increases across a period and up a group.

First Ionisation Energy

The energy required to remove one electron from one mole of gaseous atoms ($X(g) \rightarrow X^+(g) + e^-$).

Avogadro Constant ($N_A$)

The number of particles per mole, defined as $6.02 \times 10^{23}$, used to connect mass to the number of particles.

Molar Mass ($M$)

The mass of one mole of a substance expressed in units of $g \text{ } mol^{-1}$.

Diatomic Molecules

Elements that exist naturally as pairs of atoms, including $H_2$, $N_2$, $O_2$, $F_2$, $Cl_2$, $Br_2$, and $I_2$.

Ionic Bonding

The strong electrostatic attraction between oppositely charged ions, typically occurring between metals and non-metals.

Covalent Bonding

The sharing of pairs of electrons between non-metal atoms so each can achieve a full outer shell.

Metallic Bonding

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

Alloys

Mixtures of a metal with other elements, which are often harder than pure metals because different sized atoms disrupt the regular layers of ions.

Covalent Network Substances

Materials such as diamond, graphite, and silicon dioxide ($SiO_2$) that consist of a giant lattice of strong covalent bonds.

VSEPR (Electron Pair Repulsion Theory)

A model stating that electron pairs repel and move as far apart as possible, with lone pairs repelling more strongly than bonding pairs.

Polar Bond

A bond where electrons are shared unequally because one atom is more electronegative than the other.

London Dispersion Forces

Weak intermolecular forces occurring in all molecules formed when moving electrons create temporary dipoles that induce dipoles in nearby molecules.

Dipole-Dipole Forces

Intermolecular forces between polar molecules where the slightly positive end of one molecule attracts the slightly negative end of another.

Hydrogen Bonding

Strong intermolecular attraction occurring when hydrogen is covalently bonded to nitrogen ($N$), oxygen ($O$), or fluorine ($F$).

Emission Spectra

Unique patterns of coloured lines produced when electrons release energy as light while falling from higher to lower energy levels.

Enthalpy Change ($\triangle H$)

The heat energy transferred during a reaction at constant pressure, measured in $kJ \text{ } mol^{-1}$.

Exothermic Reaction

A reaction that releases energy to the surroundings; products have lower energy than reactants, and $\triangle H$ is negative.

Endothermic Reaction

A reaction that absorbs energy from the surroundings; products have higher energy than reactants, and $\triangle H$ is positive.

Specific Heat Capacity of Water ($c$)

The amount of energy required to raise the temperature of water, defined as $4.18 \text{ } J \text{ } g^{-1} \text{ } ^\text{o}C^{-1}$.

Science as a Human Endeavour (SHE)

The connection of chemical knowledge to society, technology, and the environment to solve real problems and address human needs.