Download Chemistry Vocabulary List

Chemistry Vocabulary List
Week #5
1. Nucleus => The dense central part of the atom, contains all the positive
charge, nearly all of the mass, but a very small fraction of the volume of an
atom.
2. Proton => Positively charged particle located in the nucleus of an atom;
charge = +1, mass = 1 atomic mass unit
3. Neutron => Neutrally charged particle located in the nucleus of an atom;
charge = 0, mass = 1 atomic mass unit
4. Electron => Negatively charged particle located outside the nucleus of the
atom; charge = -1, mass = 0 (mass is so small it is considered zero
compared to neutrons or protons
5. Atomic number => equal to the number of protons, used to identify the
element
6. Atomic mass (mass number) => total mass of all the sub-atomic particles
in an atom; since the mass of electrons is so small it can be ignored, then
the atomic mass = protons + neutrons
7. Isotope => atoms of the same element with different mass numbers;
atoms with the same number of protons but different number of neutrons
8. Alpha particle, or Alpha radiation => a particle created by atom undergoing
alpha decay, contains two protons and two neutrons (no electrons), mass
= 4 atomic mass units, charge = +2 (symbols: α, 42He+2)
9. Beta particle, or Beta radiation => a particle created by an atom
undergoing beta decay; charge = -1, mass = 0, essentially zero compared
to other subatomic particles (symbols: β, 0-1e-1)
10. Gamma radiation => a non-particle form of radiation produced by an atom
that is a gamma emitter; mass = 0, charge = 0 (symbol: γ)