1. Atoms, Ions, and Molecules
Chapter 2 Section 1

2. Living things consist of atoms of different elements.
ATOM – the smallest basic unit of matter
What is matter?
Something that has mass
and takes up space
ELEMENT – a group of atoms of the same type
Examples: Hydrogen, Oxygen, Carbon, Nitrogen, etc. H O

3. Parts of the Atom Nucleus (location – center of the atom) Proton
Positive Charge (+)
Neutron
Neutral Charge (0)
Energy levels (location – surrounds nucleus)
Electrons
Negative Charge (-)

4. Atomic # & Atomic Mass # of Neutrons = Atomic Mass – Atomic # Atomic #
the # of protons (or electrons)
Atomic Mass
the # of protons and # of neutrons
# of Neutrons = Atomic Mass – Atomic #

5. Use the periodic table to complete the table shown below:
ELEMENT
SYMBOL
PROTON #
NEUTRON #
ELECTRON #
Gold
Helium
Titanium
Arsenic
Mercury
Carbon
Iridium
Scandium
Nitrogen
Sodium Au 79
118 79 He 2 2 2

6. Electron Energy Levels
First Energy Level
Maximum of 2 electrons (e-)
Second Energy Level
Maximum of 8 e-
Third Energy level and beyond
Stable with 8 e- in outer shell

7. Oxygen atom (O)
Nucleus: 8 protons (+) 8 neutrons
outermost energy level: 6 electrons (-)
inner energy level: 2 electrons (-)

8. Bonding Not all atoms have full outer shells
They are not “happy” or “stable”
They form bonds with other “unhappy” atoms to complete
their outer shells
Compound – a substance made
of atoms of different elements
Examples: CO2, H20, NaCl, CH4

9. REVIEW How are elements different from compounds?
How many electrons are
needed to fill the outer
energy level of oxygen?
Compounds are made of different elements 2

10. Ionic Bonding An ion is an atom that has gained or lost
one or more electrons.
positive ions (lose electrons)
negative ions (gain electrons)
Ionic bonds form between oppositely charged ions.
Example: NaCl

12. Covalent Bond
Covalent bonds form when atoms share one or more pairs of electrons
- produce strong bonds
- examples: CO2, CH4, H2O
Molecule – two or more atoms held together by covalent bonds
- examples: N2, H2, O2, CO2, H2O

13. It’s show time….
Work as a team to develop a skit demonstrating each type of bonding!

14. REVIEW
What happens to electrons in outer energy levels when two atoms form a covalent bond?
What distinguishes one element from another?
Describe the formation of an ionic compound.
What is the difference between an ionic bond and a covalent bond?
How does a molecule differ form an atom?

15. REVIEW
What happens to electrons in outer energy levels when two atoms form a covalent bond?
Pairs of outer energy level electrons are shared
What distinguishes one element from another?
The number of protons in the nucleus
Describe the formation of an ionic compound.
One atom loses an electron, the other one gains an electron. The oppositely charged ions formed are attracted to each other.
What is the difference between an ionic bond and a covalent bond?
Electron pairs are shared in covalent bonds. Ionic bonds form when electrons are transferred and the oppositely charged ions attract.
How does a molecule differ form an atom?
A molecule is made up of two or more atoms held together by covalent bonds.

16. Exit ticket: Answer one of the questions below using complete sentences:
What part of an atom do you think would be the most fun and why?
Relationships—which type of bonding would you like to be involved in and why?

17. Investigate Van der Waal’s forces and the gecko!