Atoms and Elements

a material that cannot physically be separated into it parts

Pure Substance

the 118 building blocks of all other substances

Element

the number of elements currently known

118

smallest unit of an element that has the chemical identity of that element

Atom

an arrangement of all the known elements in order of their atomic number

Periodic Table

this tells us how many protons are in the element’s nucleus and organizes the elements on the periodic table

Atomic Number

the smallest element

Hydrogen

has an atomic number of 2

Helium

elements in a column with similar physical and chemical properties

Group

each of the seven rows in the periodic table

Period

17 metallic elements, whose chemical properties make them difficult to separate from surrounding materials

Rare Earth Elements

chart that lists all known elements

Periodic Table

positively charged parts of an atom

Protons

negatively charged parts of an atom

Electrons

neutrally charged parts of an atom

Neutrons

where the protons and neutrons are found in the atom

Nucleus

the force that holds the nucleus of an atom together

Electromagnetic

brightest star in our daytime sky

Sun

One of the first elements that we do not have much of in our bodies

Helium

First two elements the stars created

Hydrogen and Helium

represents how many protons are in the nucleus of the atom

Atomic Number