Cambridge IGCSE Chemistry: Atoms, Elements and Compounds

Vocabulary practice flashcards covering fundamental chemistry concepts from Cambridge IGCSE Chemistry 0620 Topic 2 (Atoms, Elements, and Compounds), including subatomic particles, atomic properties, and definitions of matter classifications.

Element

A pure substance made up of only one type of atom that is the simplest form of matter and cannot be broken down into simpler substances.

Compound

A substance formed when two or more different elements chemically combine, possessing unique properties different from its constituent elements and unable to be separated physically.

Mixture

A combination of two or more elements or compounds that are physically mixed together but not chemically bonded, retaining their individual properties and capable of being separated by physical means.

Atom

The smallest indivisible unit of an element and the basic building block of matter, composed of a central nucleus surrounded by orbiting electrons.

Molecule

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

Nucleus

The central core of an atom that contains protons and neutrons.

Proton

A positively charged subatomic particle found in the nucleus of an atom, with a relative charge of $+1$ and a relative mass of approximately $1$\,AMU.

Neutron

An electrically neutral subatomic particle located in the nucleus, with a relative charge of $0$ and a relative mass of approximately $1$\,AMU.

Electron

A negatively charged subatomic particle that orbits the nucleus in energy levels, having a relative charge of $-1$ and a relative mass of approximately $\frac{1}{1836}$.

Electron Shells

Specific energy levels surrounding the nucleus where electrons are arranged, with the innermost shell having the lowest energy.

Proton Number (Atomic Number)

The total number of protons in the nucleus of an atom, represented by the symbol $Z$, which identifies an element and equals the number of electrons in a neutral atom.

Mass Number (Nucleon Number)

The total number of protons and neutrons in the nucleus of an atom, represented by the symbol $A$.

Relative Atomic Mass

The average mass of all the isotopes of an element, listed at the bottom of element boxes on the periodic table.