Definitions Flashcards
atom
The smallest neutral part of an element that can take part in chemical reactions.
element
They are made up of one type of atom. Substances that cannot be split up into simpler substances.
compound
Different elements/different atoms that are chemically combined together (by chemical bonds ).
molecule
Two or more elements joined together (by covalent bonds).
Mixture
Two or more substances/elements/compounds that are not chemically combined. They are mixed together, they can usually be separated by physical methods.
chemical change
When a reaction occurs between two or more substances to create a new chemical.
physical change
A change where no new substances are formed. E.g. melting.
nucleus
The very small and dense central part of an atom.
electron
A tiny particle with a negative charge.
proton
A tiny positively charged particle found inside the nucleus of an atom.
neutron
A dense particle found in the nucleus, it carries no charge.
atomic number
The number of protons in an atom.
mass number
The number of protons plus neutrons in the nucleus of an atom.
isotopes
Atoms of the same element, which have the same number of protons (and electrons), but different number of neutrons.
