Unit 3a Science Vocab

Alkali Metals

extremely reactive metals in group 1; do not occur freely in nature

Alkaline-earth metals

metallic elements in group 2; do not occur freely in nature

atom

smallest particle into which an element can be divided

atomic number

number of protons in the nucleus of an atom

average atomic mass

weighted average of the masses of all naturally occurring isotopes of that element

chemical symbol

abbreviation for an elements name

ductile

can be made into wires

electron

negatively charged particles in an atom

electron cloud

general region around the nucleus where electrons may be found

energy levels

electrons are organized here in specific rings

group

vertical column of elements on the periodic table, sometimes called a family

halogens

toxic, nonmetals in group 17

isotope

atom of an element with different number of neutrons

malleable

able to form different shapes, bendable

mass number

total number of protons and neutrons in an atom’s nucleus

metal

shiny element that conducts heat and electricity well

metalloid

elements that have some properties of metal and some properties of non metals

neutron

uncharged particles in the nucleus of an atom

noble gases

unreactive elements that have a full valence shell; group 18

nonmetal

poor conductor of heat and electricity

nucleus

small, dense center of an atom that is positively charged

period

horizontal row of elements on the periodic table

periodic table

arrangement of the elements in order of their atomic number such that elements with similar properties fall in the same column/group

proton

positively charged particles in the nucleus

valence electrons

electrons found in the outermost energy level of an atom