Reading the Periodic Table

The top number is the atomic number or the number of ______________________Cl is an abbreviation for ______________________

The bottom number can be displayed two different ways :

The top image displays 35.453 or the ___________(the weighted average mass of the mixture of isotopes of an element)

protonsthe element name (chlorine)

atomic mass

This bottom image displays 35 or the _______________

Which equals the _______ + ________ in the nucleus

Chlorine has how many protons _____ Chlorine has how many electrons _____

35

mass number

protons neutrons

1717

On the periodic table elements are neutral therefore positive charges equal the negative charges

To determine the number of neutrons subtract protons from the mass number

Chlorine has how many neutrons ____

35

18

Rules

Atomic Number = # of ________

# of Protons = # of _________ (when atom is neutral)

Mass Number = Protons + ________ or ________ = Mass Number – Protons

protons

Electrons

Neutrons

Neutrons

PracticeElement Atomic # # Protons # Electrons Mass # # Neutrons

Lithium

Carbon

Hydrogen

Silver

3 3 3 7 4

6 6 6 12 6

1 1 1 1 0

47 47 47 108 61