physical science chapter 16 vocab

atomic mass unit

approximately 1.67 x 10^-24 g

isotopes

atoms of the same element that have different numbers of neutrons

Dmitri Mendeleev

developed an early periodic chart

period

horizontal row in the periodic table

electrons

negatively charged particles in an atom

neutrons

neutral particles in the nucleus of an atom

atomic number

number of protons in an atom's nucleus

nucleus

positively charged center of an atom

protons

positively charged particles in an atom

electron cloud

region around the nucleus where the electrons are found

electron dot diagram

represents the electrons in the outer energy level of an element

quarks

smallest known particles that make up protons and neutrons

mass number

sum of the number of protons and neutrons in the nucleus

periodic table

table of the elements showing repeated patterns in properties

atom

the smallest piece of matter that still retains the properties of the element

group

vertical column in the periodic table

average atomic mass

weighted average mass of the mixture of its isotopes