UNIT 1 Chapter 1 & 2, Chemistry

Element

Pure substances made of only one type of atom, distinguished by the number of protons in their nuclei, known as the atomic number.

Atomic Number

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

Mass Number

The total number of protons and neutrons in an atom's nucleus, indicating its overall mass.

Isotopes

Variants of an element that have the same number of protons but different numbers of neutrons, leading to different mass numbers.

Molecule

A group of two or more atoms bonded together, can be of the same or different elements.

Compound

A substance formed when two or more different elements are chemically bonded together.

Atomic Radius

The distance from the nucleus of an atom to the outermost shell of electrons.

Electronegativity

The tendency of an atom to attract electrons in a chemical bond.

First Ionisation Energy

The energy required to remove the outermost electron from a neutral atom.

Metallic Character

The tendency of an element to exhibit properties of metals, such as malleability, ductility, and electrical conductivity.

Chemical Reactivity

The tendency of an element to engage in chemical reactions.

Core Charge

The effective nuclear charge experienced by valence electrons, calculated as the number of protons minus the inner shell electrons.

Periodic Table

A table of the chemical elements arranged in order of atomic number, showing periodic trends.

SPDF Blocks

Divisions in the periodic table based on the filling of electron orbitals (s, p, d, f blocks).

Orbitals

Spaces around an atom's nucleus where electrons are likely to be found.

Subshells

Parts of electron shells identified by letters (s, p, d, f) and related energy levels.

Shells

Layers around an atomic nucleus defined by the principal quantum number (n) that can contain multiple subshells.

Covalent Bonding

The sharing of electron pairs between non-metal atoms.

VSEPR Theory

A model used to predict the shape of molecules based on electron pair repulsion.

Molecular Polarity

The distribution of electrical charge across a molecule which determines how molecules interact.

Intramuolecular Forces

Forces that hold atoms together within a molecule.

Intermolecular Forces

Forces that occur between molecules and affect physical properties.

Dispersion Forces

The weakest intermolecular forces arising from temporary electron distributions.

Dipole-Dipole Forces

Attractions between the positive end of one polar molecule and the negative end of another.

Hydrogen Bonding

A specific strong type of dipole-dipole interaction, important for water and biological molecules.

Allotropes

Different forms of the same element, e.g., diamond and graphite.

Covalent Lattice

A strong, 3D structure of atoms bonded by covalent bonds.

Covalent Layer Lattice

Layers of covalently bonded atoms held together loosely.

Covalent Network Lattice

A strong structure where atoms are interconnected by covalent bonds throughout.

Tetrahderal

Shape with one central atom and four surrounding atoms.

Trigonal Pyramidal

Shape with one central atom, three surrounding atoms, and one lone pair.

Delocalized Electrons

Electrons that can move freely across multiple atoms.

Atom

the fundamental unit of matter, the smallest building blocks of elements