1. Periodic Table Notes Unit 3 – Notes

2. Periodic Table
Nonmetals are on the right side of the periodic table (with the exception of H).

3. Periodic Table
Metals are on the left side of the chart.

4. Periodic Table
Metalloids border the stair-step line (with the exception of Al, Po, and At).

5. Diatomic Molecules
These seven elements occur naturally as molecules containing two atoms.

6. Ions When atoms lose or gain electrons, they become ions.
Cations are positive and are formed by elements on the left side of the periodic chart.
Anions are negative and are formed by elements on the right side of the periodic chart.

7. Development of Periodic Table
Elements in the same group generally have similar chemical properties.
Physical properties are not necessarily similar, however.

8. Development of Periodic Table
Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.

9. Metals versus Nonmetals
Metals tend to form cations.
Nonmetals tend to form anions.

10. Metals
They tend to be lustrous, malleable, ductile, and good conductors of heat and electricity.

11. Nonmetals
These are dull, brittle substances that are poor conductors of heat and electricity.
They tend to gain electrons in reactions with metals to acquire a noble gas configuration.

12. Metalloids
These have some characteristics of metals and some of nonmetals.
For instance, silicon looks shiny, but is brittle and fairly poor conductor.

13. Periodic Trends
In this chapter, we will rationalize observed trends in
Sizes of atoms and ions.
Ionization energy.
Electronegativity

14. What Is the Size of an Atom?
The bonding atomic radius is defined as one-half of the distance between covalently bonded nuclei.
Measured in nanometers

15. Nuclear Charge The positive charge of the protons
For example sodium has a nuclear charge of +11

16. Sizes of Atoms Bonding atomic radius tends to…
…decrease from left to right across a row
…increase from top to bottom of a column

17. Atomic Radius

18. Ionization Energy
The ionization energy is the amount of energy required to remove an electron from the ground state of an atom.
The first ionization energy is that energy required to remove first electron.
The second ionization energy is that energy required to remove second electron, etc.
Measured in J or kJ

19. Ionization Energy
It requires more energy to remove each successive electron.
When all valence electrons have been removed, the ionization energy takes a quantum leap.

20. Trends in First Ionization Energies
As one goes down a column, less energy is required to remove the first electron.
For atoms in the same group, Zeff is essentially the same, but the valence electrons are farther from the nucleus.

21. Electronegativity A measure of how well you attract electrons.
A scale of 0 – 4
Created by Linus Pauling