1. Chapter 5: a closer look at matter
The nuclear atom
Chapter 5: a closer look at matter

2. Essential questions What is the atomic theory?
How do electrons orbit around the nucleus?
How does truth in science change over time?
Assessment: Presentation & Test

4. Where do elements come from?
Atoms in your body are nearly 14 billion years old
Every single atom in your body was created in a star billions of years ago
Young star is made up of hydrogen. Other elements created via thermonuclear reactions.
You are made of stardust!
What kind of atoms make up your body?
118 elements on the periodic table.

5. And… you continue to regenerate!
How many time have you shed your skin?
Number of times you have changed your skin =
Your age x number of days since your last birthday 28
Skin is largely made up of keratin
Membrane: Phospholipid bilayer

6. Review: Inside an atom Proton = positively charged subatomic particle
Neutron = subatomic particle with mass equal to proton but no electric charge
Nucleus = center of an atom, composed of protons and neutrons
Electron = negatively charged particle
Electron cloud = space around the nucleus of an atom where atom’s electrons are found
Manipulate atom:
Particle
Charge
Mass in grams
Proton +1
1.67 x 10-24
Neutron
Electron -1
9.11 x 10-28

7. Inside an atom – Particle physics
Quarks and leptons are families of particles (6 members in each family)
Quarks have fractional charges (e.g. +2/3) and leptons have integer charges (e.g. -1)
Atomic structure
Proton: composed of quark
Electron: composed of leptons
Neutron: composed of quark

8. The rule for finding out the number of protons, neutrons, electrons
Atomic number = number of protons, number of electrons (if neutral)
Mass number = number of protons and neutrons

9. Ions
An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

10. Isotopes
Isotopes = have nucleus with the same number of protons but different number of neutrons
Therefore, isotopes have different mass numbers
Combination of isotopes make up the average atomic mass that you see on the periodic table
Unstable atoms are radioactive, nucleus can decay or change by emitting radiation

11. Examples Mass Protons Neutrons Electrons Charge Symbol Ca N S Ba +2 F-1 -3 K 20 21