Intro to atoms PPT

1. Imagine cutting a gold bar in half.
Then cut in half again.
…and again.
…and again.
…and again.
…and again.
Speak up! Could you keep cutting that bar in half
forever? Why or why not?
How small could you cut up that gold and it still
be gold?

2. Atoms

3. An Atom Apart Reading/Highlighting Guide
1. According to the text, what are atoms?
2. What does the Greek word a’tomos mean?
3. What are atoms made of?
4. What decides the chemical element of an
atom?
5. What determines the chemical properties
of an atom?

4. • What is an atom?
• An atom is the smallest particle into which
an element can be divided and still be the
same substance.
• Atoms make up elements and elements
combine to form compounds.

5. • What is an atom?
• An atom is made of 3 parts:
• Protons (+)
• Neutrons (neutral)
• Electrons (-)
• Protons and neutrons make up the nucleus
of the atom
• Electrons orbit around the nucleus like
planets around the sun*
*Actually this is not true but it is a useful analogy

6. • Key terms:
• Valence electron – electrons farthest from
the nucleus (involved in bonding)
• Atomic number* = number of protons.
*Determines the identity of an element
• Mass number = # of protons + # of neutrons
• Atomic mass = the average mass of all the
known isotopes of an element

7. • Even though it is not quite accurate anymore,
the Bohr model of the atom is still useful for
building a basic understanding of atoms.

8. Practice:
Draw an atom and label its parts. Your
drawing should include:
• 3 Protons (+)
• 3 Neutrons (neutral)
• 3 Electrons (-)
• Nucleus
Your drawing should fill an entire page!

9. Divide your page as shown and draw an atom of each of the
following elements.
Helium atom Beryllium atom
Carbon atomBoron atom

10. • Cold calls…
1. What are the three subatomic particles in an atom? (Be
sure to include their charges!)
2. What 2 subatomic particles are in the nucleus of an atom?
3. Where are electrons found in an atom?
4. What determines the chemical element of an atom?
5. What is a valence electron?
6. What is the difference between atomic mass and mass
number?
7. What is the charge of the nucleus? Why?
8. What is the charge of the atom as a whole? Why?

11. Divide your page as shown and draw an atom of each of the
following elements.

12. Speak Up! Compare and contrast the atoms
pictured below

13. Quick Quiz: Draw and label an atom of the
element nitrogen.