elements and periodicity

Atomic number (Z)

The number of protons in the nucleus of an atom, which also equals the number of electrons in a neutral atom.

Atomic mass (Ar)

The average mass of an atom, typically measured in atomic mass units (amu), reflecting the total number of protons and neutrons.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses.

Radioactive elements

Elements that have unstable nuclei and therefore lose energy by emitting radiation, often causing them to glow.

Periodic Table

A tabular arrangement of the elements in order of increasing atomic number, which reflects periodic trends in their properties.

Alkali metals

Group 1 elements in the periodic table, known for their high reactivity and presence in nature primarily as compounds.

Halogens

Group 17 elements which are highly reactive nonmetals, often found in nature as diatomic molecules.

Noble gases

Group 18 elements that are characterized by their lack of reactivity due to having a full valence shell of electrons.

Mass Spectrometry

An analytical technique used to measure the mass-to-charge ratio of ions, allowing for the determination of isotopic compositions.

Electron configuration

The distribution of electrons in an atom's orbitals, which influences its chemical behavior and interactions.

Proton

A positively charged subatomic particle found in the nucleus of an atom, with an atomic mass unit of approximately 1.

Neutron

A neutral (no charge) subatomic particle found in the nucleus of an atom, with an atomic mass unit of approximately 1.

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom, with a very small mass compared to protons and neutrons.

Valence electrons

Electrons located in the outermost electron shell of an atom, which are involved in chemical bonding and determine an element's reactivity.

Ionisation Energy (IE)

The energy needed to create an ion from an atom.

Sub-shells

Designated as s, p, d, and f, they contain fixed numbers of electrons in an electron shell.

Electron Configuration

The distribution of electrons in an atom's orbitals, represented using quantum numbers.

Excitation of Electrons

High energy promotes electrons to higher energy levels, resulting in light emission when they drop back down.

Oxidation

The process of losing electrons, often seen in reactions involving metals.

Reducing Agents (RA)

Substances that bring about reduction by providing electrons.

Oxidising Agents (OA)

Substances that bring about oxidation, accepting electrons in the process.

Noble Gas Structure

A state where an atom has full outer electron shells, achieved by gaining or losing electrons.

Electron Shells

Regions surrounding the nucleus of an atom, where electrons reside in quantised energy levels.

Periodic Trends

Patterns observed in properties of elements, including atomic radius and ionisation energy.

Sodium Ionisation Energy Pattern

Reflects the electron structure of sodium, with one outer electron controlling its chemical properties.

Trends in Ionisation Energy

Generally, ionisation energy decreases down a group and increases across a period.

Principal Quantum Numbers

Numbers (n=1, 2, 3, …) that represent the energy level of electrons in an atom.

Electron Bombardment

A method where electrons are emitted into gases to ionize them for spectral studies.

Atomic Emission Spectra

Light emitted by electrons as they transition between energy levels, useful in identifying elements.

Binding Energy

The energy required to remove an electron from an atom; equivalent to ionisation energy in context.

Practical Classes

Classes that involve hands-on activities for students, starting in week 5.

Ionisation Energy (IE)

The energy needed to create an ion from an atom.

Electron Configuration

The distribution of electrons among the various orbitals of an atom.

Quantum Numbers

Numbers that describe the unique quantum state of an electron in an atom.

Sub-shells

Subdivisions of electron shells that contain orbitals where electrons are likely to be found.

Oxidation

The process of losing electrons during a reaction.

Reduction

The process of gaining electrons during a reaction.

Noble Gas Structure

The electronic configuration of a noble gas, characterized by a full outer shell of electrons.

Orbitals

Regions around the nucleus of an atom where electrons are likely to be found.

Periodic Trend

Patterns in the properties of elements that are evident from the periodic table.

Effective Nuclear Charge

The net positive charge experienced by an electron in a multi-electron atom.

Electronegativity

A measure of an atom's ability to attract and hold onto electrons.

Atomic Radius

The distance from the nucleus to the outer boundary of the surrounding cloud of electrons.