Atomic Notations

Chapter 3

Atoms: The Building Blocks of Matter

Section 3: Counting Atoms

Atomic Number

●Number of protons

●Same for all atoms of same element

●Above symbol on periodic table

Isotopes

●Same number protons, different number neutrons

●Different mass

Mass Number

●Protons + neutrons

●Isotopes identified by element name and mass number

●Nuclide - term for specific isotope of an element

●Written in 2 ways:

Atomic #

Mass #

lithium-6

Practice

How many protons, neutrons, and electrons are in an atom of chlorine-35?

Multiple Choice

How many protons, neutrons, and electrons are in an atom of Chlorine-35?

• 17 protons, 18 neutrons, 17 electrons

• 18 protons, 17 neutrons, 18 electrons

• 17 protons, 17 neutrons, 17 electrons

• 17 protons, 17 neutrons, 18 electrons

Multiple Choice

How many protons, neutrons, and electrons are in an atom of Bromine-80?

• 35 protons, 40 neutrons, 36 electrons

• 35 protons, 35 neutrons, 35 electrons

• 35 protons, 45 neutrons, 35 electrons

• 35 protons, 80 neutrons, 35 electrons