Transition from GCSE to A Level Chemistry

Comprehensive vocabulary flashcards covering key definitions, fundamental atomic concepts, SI prefixes, and core calculation formulas for transitioning from GCSE to A Level Chemistry.

Proton

A subatomic particle located in the nucleus with a relative mass of 1 and a relative charge of $+1$.

Neutron

A neutral subatomic particle located in the nucleus with a relative mass of 1 and a relative charge of 0.

Electron

A subatomic particle that orbits the nucleus with a relative mass of $\frac{1}{1840}$ and a relative charge of $-1$.

Atomic number

The number of protons in the nucleus of a single atom of an element.

Mass number

The total number of protons plus the number of neutrons in an atom.

Ion

An atom, or group of atoms, with an electrical charge.

Mass spectrometer

An instrument that accurately determines the mass and abundance of separate atoms or molecules to help identify them.

Mass spectrum

The output from a mass spectrometer that shows the different isotopes that make up an element.

Electron shell maximum capacity

The total number of electrons that each electron shell (main energy level) can contain, calculated as $2n^2$ electrons, where $n$ is the shell number.

Electron sub-shells (orbitals)

Subdivisions within an electron shell, designated in order as $s$, $p$, $d$, and $f$, each orbital holding a maximum of 2 electrons.

Ionisation energy

The energy required to remove a mole of electrons from a mole of atoms in the gaseous state, given in units of $kJ\,mol^{-1}$.

Relative atomic mass ($A_r$)

$$\text{relative atomic mass} = \frac{\text{average mass of 1 atom}}{\frac{1}{12}^{\text{th}}\text{ mass of 1 atom of }^{12}\text{C}}$$

Relative molecular mass ($M_r$)

$$\text{relative molecular mass} = \frac{\text{average mass of 1 molecule}}{\frac{1}{12}^{\text{th}}\text{ mass of 1 atom of }^{12}\text{C}}$$

Standard form

A scientific notation writing format of $A \times 10^x$, where $A$ is a number from 1 to 10 and $x$ represents the number of places the decimal place is moved.

Giga- ($G$)

An SI prefix representing a multiplication factor of $10^9$.

Mega- ($M$)

An SI prefix representing a multiplication factor of $10^6$.

Kilo- ($k$)

An SI prefix representing a multiplication factor of $10^3$.

Centi- ($c$)

An SI prefix representing a multiplication factor of $10^{-2}$.

Milli- ($m$)

An SI prefix representing a multiplication factor of $10^{-3}$.

Micro- ($\mu$)

An SI prefix representing a multiplication factor of $10^{-6}$.

Nano- ($n$)

An SI prefix representing a multiplication factor of $10^{-9}$.

Conservation of mass

The law stating that during chemical reactions, atoms are not created or destroyed but rearranged, meaning the total mass before the reaction equals the total mass after.

Concentration

The amount of solute, in moles, dissolved in $1\,dm^3$ (or 1 litre) of solution, calculated as $c = \frac{n}{V}$ and typically expressed in units of $mol\,dm^{-3}$ or $g\,dm^{-3}$.

Molar mass ($M$)

The mass per mole of a substance, expressed in units of $g\,mol^{-1}$, calculated by summing the atomic masses of all constituent atoms in the chemical formula.

Amount of substance ($n$)

The quantity of a substance in moles, given by the relationship $n = \frac{m}{M}$, where $m$ is mass in grams and $M$ is molar mass in $g\,mol^{-1}$.

Percentage yield

A measure of reaction efficiency calculated as: $\text{percentage yield} = \frac{\text{actual amount (in moles) of product}}{\text{theoretical amount (in moles) of product}} \times 100\%$.

Percentage error

The measurement uncertainty of a piece of apparatus calculated as: $\text{percentage error} = \frac{\text{maximum error}}{\text{measured value}} \times 100\%$.