2. How small is an atom?
Three One-Hundred-Millionths of a
Centimeter!
Measured using the unit “amu”
(atomic mass unit)
3. What is an atom made of?
The Nucleus
Protons (Positive charged particles)
○ Neutrons (Neutral-no charge)
Outside the Nucleus
Electrons (Negative charged particles)
○ Found around the nucleus within electron clouds-
called orbitals
*** Think about it: Why are the electrons to pulled
into the nucleus?
4. What is an atom made of?
Particle Location Charge Size
Proton In the nucleus + 1 amu
Neutron In the nucleus N/A (none) 1 amu
Electron Outside the
nucleus
- 0 amu
(almost no mass!)
5.
6. How do we figure out how many
protons, electrons and neutrons are in
an atom?
Atomic # = number of electrons
Atomic # = number of protons
Atomic mass – atomic # = Number of neutrons
*** Calculate the number of protons, electrons
and neutrons in Carbon***
7. How are different elements created?
○simply add protons, neutrons, and
electrons
○Adding protons = changing elements
○Adding or subtracting electrons = ions
○Adding or subtracting neutrons =
isotopes
○ https://www.brainpop.com/science/matterandchemistry/isotopes/
8. What are the types of ions?
Cation – positively charged ion
One or more electrons have been removed
Anion – negatively charged ion
One or more electrons have been added
https://www.brainpop.com/science/matterandchemistry/ions/
9. Summary: Reading your
periodic table
1. List two Noble gases.
2. List two Non-metals.
3. List two Metals
4. What does the atomic mass represent?
5. What does the atomic number
represent?
6. Where are the noble gases?
7. How many protons, electrons and
neutrons are in Li, O, C, Cl and Ar?
