science ch 4 vocab Flashcards
An atom’s central region which is made up of protons and neutrons.
Nucleus
A subatomic particle that has a positive charge and that is found in the nucleus of an atom.
Proton
A subatomic particle that has no charge and that is found in the nucleus of an atom.
Neutron
A subatomic particle that has a negative charge.
Electron
An electron that is found in the outer-most shell of an atom and that determines the atom’s chemical properties.
Valence electron
The law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements.
Periodic law
A horizontal row of elements in the periodic table.
Period
A vertical column of elements in the periodic table.
Group
An atom or group of atoms that has lost or gained one or more electrons and has a negative or positive charge.
Ion
The number of protons in the nucleaus of an atom.
Atomic number
The sum of the numbers of protons and neutrons in the nucleus of an atom.
Mass number
An atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons.
Isotope
A unit of mass that describes the mass of an atom or molecule; it is exactly one-twelfth of the mass of a carbon atom with mass number 12.
Atomic mass unit (amu)
The weighted average of the masses of all naturally occurring isotopes of an element.
Average atomic mass
Average atomic mass
The weighted average of the masses of all naturally occurring isotopes of an element.
An element that is shiny and conducts heat and electricity well.
Metal
Nonmetal
An element that conducts heat and electricity poorly.
An element or compound that conducts electric current better than an insulator but not as well as a conductor does.
Semiconductor
Alkali metal
One of the elements of Group 1 of the periodic table.
Alkaline-earth metal
One of the elements of Group 2 of the periodic table.
One of the elements of Groups 3-12 of the periodic table.
Transition metal
One of the elements of Group 17 of the periodic table.
Halogen
An unreactive element of Group 18 of the periodic table.
Noble gas
The SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in 12 g of carbon-12.
Mole
