This document provides information on atomic structure including subatomic particles like electrons, protons, and neutrons. It defines these particles and their properties such as charge. It describes how atoms have no overall charge when the number of protons and electrons are equal. It also defines atomic number as the number of protons and mass number as the total number of protons and neutrons in an atom. Formulas are provided to calculate these values and the number of neutrons from the periodic table. Ions are also introduced as atoms that have gained or lost electrons, becoming positively or negatively charged.

1. ATOMIC STRUCTURE
Take these notes on page 31 in your notebook.
Use the Cornell Method of Note taking. Label
and Date the page.

2. SUBATOMIC PARTS
Electrons
Represented with lower case (e)
In electron shells or energy levels around
the nucleus
Negatively charged (-)

3. SUBATOMIC PARTS
Protons
-Represented with lower case (p)
-In nucleus
-Positively charged (+)

4. SUBATOMIC PARTS
Neutrons
-Represented with lower case (n)
-In nucleus
-No charge (neutral)

5. SUBATOMIC PARTS
Atoms have no charge
The # of protons = # of electrons
The proton (+) and electron(-) cancel
each other out. Neutrons have no
charge.

6. SUBATOMIC PARTS
Draw an atom
and label the
subatomic
parts in your
notes!

7. ATOMIC NUMBER
Represented by capital Z.
Z = the number of protons in an atom

8. ATOMIC NUMBER

9. ATOMIC NUMBER
 Use the periodicTable on page 288-289 in your
textbook to find the symbols and atomic number
of the following elements:
Selenium
Zinc
Caesium
Chromium

10. MASS NUMBER
“Electrons are to protons as fleas are to an elephant – the
proton being the elephant. When we calculate the mass
of an elephant, we don’t add on the mass of the
elephant‘s fleas, and when we calculate the mass of an
atom, we don’t add the mass of the electrons.” ~Joy of
Chemistry, Cobb & Fetterrolf
~it takes the mass of 1837 electrons to equal the mass of
1 neutron or proton

11. MASS NUMBER
Since electrons weigh so little they are not
included in calculating atomic mass.
Mass number is represent by capital (A)
Mass Number is calculated by adding the
number of protons and the number of neutrons
Mass number = atomic number + number of
neutrons
A = Z + number of neutrons

12. MASS NUMBER

13. MASS NUMBER
Use the periodicTable on page 288-289 in your
textbook to find the symbols and mass number of
the following elements:
Molybdenum
Osmium
Titanium
Sulphur

14. MASS NUMBER
We can use the mass number to calculate the number of
neutrons:
Number of neutrons = mass number – atomic number
Neutrons = A - Z

15. NUMBER OF NEUTRONS
Using the atomic numbers and mass numbers you
found to calculate the number of neutrons in:
Molybdenum
Osmium
Titanium
Sulphur
Selenium
Zinc
Caesium
Chromium

16. IONS
Ions are electrically charged particles
If an atom loses one or more electrons it
becomes positively charged (K+)
If an atom gains one or more electrons it
becomes negatively charged (Cl-)

17. DIDYOU LABEL AND DATEYOUR PAGE?
Complete your Notes
with a Summary and
Main Ideas or Questions
in the Left column!