ABEKA Physical Science 6.2 Inside the atom

Thompson atom

"plum pudding"

atomic mass unit (u)

1/12th of the mass of a carbon atom with mass number 12 (C-12)

nucleon

Particles found in the nucleus - protons and neutrons

ion

an atom that has gained or lost electrons and is no longer electrically neutral

isotopes

atoms with same atomic number (no. of protons) but different numbers of neutrons in the nucleus

quarks

believed to be the building blocks for all other particles

electron shell

concentric layers that hold the electrons in an atom

electrically neutral

contains the same number of protons and electrons

nucleus

dense central core of every atom

Bohr atom

electrons in circular orbits around nucleus at specific energy levels

Dalton atom

hard sphere

different isotopes

have the same atomic number but different mass number

electron

negatively charged particle found outside the nucleus

neutron

particle with no electrical charge

subatomic particles

particles that atoms are composed of. They are smaller than atoms.

proton

positively charged particle

mass number

sum of the number of protons and neutrons in an atom.

atomic number

the number of protons in an atom's nucleus. It uniquely identifies the element.