Chemistry Lecture Notes on Atoms and Compounds

A set of vocabulary flashcards based on key concepts from a chemistry lecture on atoms, elements, and compounds.

Atom

The basic unit of a chemical element, comprising a nucleus and electrons.

Nucleus

The central part of an atom, containing protons and neutrons.

Proton

A positively charged particle found in the nucleus of an atom.

Neutron

A neutrally charged particle found in the nucleus of an atom.

Electron

A negatively charged particle that orbits the nucleus of an atom.

Ion

An atom that has gained or lost electrons, resulting in a net charge.

Chemical symbol

A one or two-letter notation used to represent an element.

Mass number

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

Atomic number

The number of protons in the nucleus of an atom, also equal to the number of electrons.

Element

A pure substance that cannot be broken down into simpler substances by chemical means.

Compound

A substance consisting of two or more different elements chemically bonded together.

Isotope

Different atomic forms of the same element, having the same number of protons but a different number of neutrons.

Relative atomic mass (Ar)

The average mass of the isotopes of an element, weighted by their relative abundance.

Mole

A unit measuring the amount of substance, defined as 6.02 x 10^23 atoms.

Balanced equation

A chemical equation where the number of atoms of each element is the same on both sides.

Percentage composition

The percentage by mass of each element in a compound.

Relative molecular mass (Mr)

The total mass of a compound calculated by adding the relative atomic masses of all atoms in the formula.