Atoms, Isotopes and types of bonding

1. Elements, Compounds and
States of Matter

2. The Periodic Table
• 92 naturally occurring elements
• Each element has a distinct atomic number that describes the
number of protons and electrons a neutral atom
• The atomic weights represent the number of protons and
neutrons in the nucleus of the atom.
• Since atoms of the same element may have different masses
due to a difference in the number of neutrons, atomic masses
are expressed in decimal
averages.
• These different forms of
the same element are
called isotopes.

3. Create symbols for
the following elements
• Helium
• Oxygen
• Calcium
• Silicon
• Iron
• Aluminum
• Sodium
• Magnesium

4. Elements in the Universe
and on Earth
• Astronomers have identified hydrogen and
helium as the most abundant elements in the
Universe
• The most abundant elements on Earth are
oxygen, silicon, aluminum, iron, calcium,
sodium, potassium and magnesium
• Does this make sense? Why, or why not?

5. The Atom
• Electrons are found in energy levels surrounding the proton/neutron filled
nucleus
• These electrons do not follow traditional paths. Their location can be
described in terms of probability.

6. Determining the number of protons,
neutrons, and electrons
• The atomic number = electrons and protons
• The mass – atomic number= neutrons
Example: Helium
• 2 electrons, 2 protons
• 2 neutrons

7. The atomic number = electrons and protons
The mass – atomic number= neutrons
Practice:
For each of the symbols you made before,
find the number of electrons, protons, and
neutrons

8. Isotopes
• They have the same number of protons but a different number of
neutrons
• They are heavier because of the extra neutron(s)
• Certain atomic isotopes are unstable and give off radioactive energy
• Exp. Helium (4-Helium)

9. Isotope Practice
• Complete the question for Carbon
Isotopes.
• Identify the number of protons,
electrons, and neutrons for each.

10. Importance of Isotopes
Help scientists understand the origins of the universe and the earth
• Big Bang created both Helium and Hydrogen
• Supernova created the rest of the elements
• Cosmic Ray crashes created isotopes

11. Carbon Dating using C-14
• An isotope of Carbon, Carbon -14, is used by
scientists as a way of dating archeological remains
• How? Carbon-14 is an unstable isotope which means
that with time it will decay and turn into nitrogen. It
takes 5730 years for half of the C-14 isotope to have
decayed into nitrogen. This is called the half-life.
• It can be used to date things as old as 65 000- 80 000
years old

12. Compounds
Covalent compounds make up molecules
• Molecular compounds SHARE electrons and usually
occur between non-metals
• Molecular compounds may be polar (unequal
electron sharing) or nonpolar (equal electron
sharing)
Ionic compounds make up ionic compounds
• Ionic compounds transfer electrons and stay bonded
through electronegative force

14. Metallic bonds
• Extremely organized and structured lattice of
positive metal ions in a ‘sea of electrons’

15. States of Matter
• Solids -> crystalline structure
• Liquids -> vibrations in any material begin to occur at 0 K (−
273.15°C). Upon reaching a melting point, the vibrations
break forces holding the solid structure together
• Gases-> when more energy is introduced liquids may change
into gases through evaporation. Particles in this states are far
away from each other and travel randomly.
• Plasma -> matter existing at temperatures greater than 5000
degrees Celsius experience collisions that knock electrons
away from nuclei. This produces a hot, ionized, electrically
conductive gas

17. Plasma video

18. 2.1 Portfolio Questions
- Complete two exercises