1. The Periodic Table
Overview of Chapter 20

2. Metals Metals- good conductors of heat & electricity.
All but one (Hg) are solid at room temperature.
Lustrous- reflect light
Malleable- can be hammered or rolled into sheets,
Ductile- can be drawn into wires
Metals- have 1-3 valence electrons, so they lose electrons to become stable- they become cations
Metallic bonding- positively charged metallic ions are surrounded by a cloud of electrons.
Outer electrons are not held tightly and can move among the ions- allows conduction of electricity

3. Metallic bonding

4. Metals
Alkali- Group 1 A very reactive because they have 1 valence electron
Alkaline earth- Group 2A- fairly reactive- have 2 valence electrons
Transition elements- Groups 3-12 or 1B-8B, metals, often form colored compounds
Lanthanides are elements after lanthanum and many are used to produce colors on our TV screens
Actinides- follow actinium. All are radioactive and unstable, so they are difficult to research

5. Metals Elements beyond Uranium are radioactive-
As # of protons increases, the repulsive force within the nucleus also increases- forces the atom to break apart.
(Radioactive substances are substances in which the nucleus breaks down and gives off particles and energy )

6. Nonmetals Nonmetals- gases or brittle solids at room temperature.
not malleable or ductile.
do not conduct heat or electricity well
not shiny
Nonmetals don’t conduct electricity because- electrons are strongly attracted to the nucleus
Gain electrons to form anions
Can form either covalent or ionic bonds
Covalent- shared electrons
Ionic- gain and loss of electrons

7. Nonmetals
Diatomic- molecule that consists of two atoms of the same element covalently bonded
Includes (memorize these!!)
H2 Cl2 F2 N2 O2 Br2 I2
Hydrogen is diatomic because it is very reactive.
Bonding makes it more stable
Halogens- nonmetals from group 7A or 17.
very reactive.
7 valence electrons
form reactive diatomic molecules with distinctive colors
Noble gases- stable due to full outer energy levels.
don’t make compounds naturally

8. Metalloid Metalloid- can form ionic or covalent bonds.
properties of both metals and nonmetals
Semiconductor- element that conducts electric current under certain conditions- like Silicon (Si is a metalloid)

9. Allotropes
Allotrope- same element with different forms and different properties
Example: Diamond and graphite
Both are made of carbon.
Diamond- clear, hard
each C atom bonded to four other C atoms forming a giant crystal.
Graphite- black powder with hexagonal layers of C atoms.
Each C is bonded to 3 other C.
Layers can slide past each other, so graphite is a good lubricant.

10. Diamond and graphite