Atoms, Definitions Flashcards
Atom
the particles that make up all materials; the smallest part of an element that can take part in a chemical reaction
Atomic number
the number of protons in an atom
Mass number
the number of particles in the nucleus (protons + neutrons)
Bohr model
In the Bohr model of the atom, electrons travel in defined circular orbits around the nucleus.
Nucleus
the heavy core at the centre of an atom, made of protons and neutrons
Standard atomic notation
A way of writing the elements symbol, mass number, and atomic number
Valence shell
The outermost shell in an atom. Electrons in this shell participate in chemical reactions
Halogen gases
Group 17 elements, gain one electrons (-)
Noble gases
Group 18 elements, elements in this group do not lose, gain or share electrons. This is why noble gas elements do not take part in chemical reactions.
Alkaline metals
Group 1 elements, lose one electron (+)
Alkaline earths (Alkaline earth metals)
Group 2 elements, lose two electrons (2+)
