2.1.1-2.1.2-atomic-structure

Proton

A sub-atomic particle found in the nucleus of an atom with a relative mass of 1 and a positive charge of +1.

Neutron

A sub-atomic particle found in the nucleus of an atom with a relative mass of 1 and no charge (0).

Electron

A sub-atomic particle that orbits the nucleus of an atom, with a relative mass of 1/1800 and a negative charge of -1.

Atomic Number (Z)

The number of protons in the nucleus of an atom, which determines the element's identity.

Mass Number (A)

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

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Relative Atomic Mass

The weighted mean mass of one atom compared to one twelfth of the mass of one atom of carbon-12.

Relative Isotopic Mass

The mass of one isotope compared to one twelfth of the mass of one atom of carbon-12.

Relative Molecular Mass

The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12.

Relative Abundance

The proportion of a particular isotope in a mixture of isotopes of an element.

Spectator Ions

Ions that do not participate in the actual chemical reaction and remain unchanged.

Ionic Equation

An equation that only shows the ions that are directly involved in a chemical reaction.

Lithium Sulfate Formula

Li2SO4, combining two lithium ions (Li+) to balance the -2 charge of the sulfate ion (SO4 2-).

Calcium Phosphate Formula

Ca3(PO4)2, combining three calcium ions (Ca2+) to balance two phosphate ions (PO4 3-).

Probabilities in Mass Spectrometry

The likelihood of finding a specific isotope of an element, which affects the peaks in mass spectrometry results.

Copper Isotopes

Copper has two isotopes, 63-Cu and 65-Cu, with a relative atomic mass of 63.5.

Calculation of Relative Atomic Mass

R.A.M. is calculated using R.A.M = Σ (isotopic mass x % abundance) / 100.

Weighted Mean Mass

An average mass that takes into account the relative abundance of different isotopes.

Chemical Reaction Example

The ionic equation Pb2+ (aq) + 2Cl- (aq) → PbCl2 (s) demonstrates the key changes in a reaction.

Diatomic Molecules

Molecules consisting of two atoms, which can be of the same or different elements.

Mass Spectrometry

A technique used to determine the mass-to-charge ratio of ions to identify and quantify substances.

Periodicity

The repeating pattern of chemical and physical properties of the elements when they are arranged by increasing atomic number.

Electronegativity

A measure of the tendency of an atom to attract a bonding pair of electrons.

Ionic Bond

A chemical bond formed between two ions with opposite charges, resulting from the transfer of electrons.

Covalent Bond

A chemical bond that involves the sharing of electron pairs between atoms.

pH Scale

A scale used to specify the acidity or basicity of an aqueous solution, ranging from 0 (most acidic) to 14 (most basic).

Catalyst

A substance that increases the rate of a chemical reaction without being consumed in the process.

Equilibrium

A state in a reversible chemical reaction where the rates of the forward and backward reactions are equal.

Molarity

A measure of concentration representing the number of moles of solute per liter of solution.

Concentration Gradient

A difference in the concentration of a substance across a space, which drives the movement of particles.

Redox Reaction

A chemical reaction that involves the transfer of electrons between two species, leading to changes in their oxidation states.