1. What are they and what do they do?
2/23/2019
Atoms
What are they and what do they do?

2. What are atoms? Atoms are the smallest particles of matter
Atoms make up everything around us
Molecules are combinations of atoms
Elements are only one type of atom
Compounds are made up of different types of atoms
Hydrogen Gas
Water
Dan Kelly - Magic of Electrons - PLTW - Atoms

3. Components of an Atom Nucleus. Protons: (+) Neutrons: Electrons: (-)
2/23/2019
Components of an Atom
At the center of all atoms is the
Nucleus.
The nucleus contains protons
and neutrons.
Protons: (+)
Positively charged atomic particles
Neutrons:
Uncharged (neutral) atomic particles
Orbiting around the nucleus are the
electrons.
Electrons: (-)
Negatively charged atomic
Particles
Demonstration on positive vs. negative
Dan Kelly - Magic of Electrons - PLTW - Atoms

5. Periodic table
Vertical columns- groups. Horizontal rows- periods. Periodic table used to be arranged in order of increasing atomic mass but they are now arranged so that vertical columns (groups) have similar properties. They also have the same number of electrons in their outer electron shell.

8. Helium
Protons: 2
Electors: 2
Neutrons: – 2 = = 2

9. Try this one yourself.

10. Potassium
Protons: 19
Electrons: 19
Neutrons: 39.1 – 19 = 20.1 = 20

11. Questions
Calculate the number of protons, neutrons, and electrons for the following:

12. Chemical Science
We know that substances are made of atoms and molecules. When an chemical change occurs, the atoms in the molecules re-arrange to form different combinations. The substances we start with are called reactants The substance we end up with are called products Reactants Products

13. Atomic Number Atomic Number = The number of protons
And for an element the number of protons will equal the number of electrons.

14. Atomic Mass
Atomic Mass = The number of protons + The number of neutrons
If we subtract the Atomic number from the Atomic mass then we are left with just the number of Neutrons for that element.
Atomic mass-Atomic number= number of neutrons