1. The Periodic Table
&
Periodic Law

2. Meyer & Mendeleev
In 1869, published almost identical versions with the elements in order of increasing atomic mass and in columns with similar properties.

3. Periodic Law
There is a periodic repetition of chemical and physical properties of the elements when they are arranged in order of increasing atomic number

4. Arrangement of the Periodic Table
Groups/Families
18 vertical columns (↑↓)
Two Labeling Systems
Number-and-letter system
1A through 8A columns (representative elements)
1B through 8B short columns (transition elements)
2. Number system, Group 1 to Group18
Periods
7 horizontal rows (↔)

5. Non-Metals
Metalloid
Non-Metals
Metals
Metals

6. Metals - Properties Shiny Solid at room temperature
Good conductors of heat and electricity
Malleable
Ductile

7. Nonmetals & Metalloids
Dull
Generally gases or brittle solids at room temperature
Poor conductors of heat and electricity
Metalloids
Elements with physical and chemical properties of both metals and nonmetals
Rest on the “stair-step” B Si As Te At Ge Sb Po
←Metals

8. Periodic Trends

9. Atomic Radius
Half the distance between two nuclei of identical atoms that are chemically bonded together
Down the group
atomic radius increases,
because…
Across the period
atomic radius decreases,
becauses….

10. Ionization Energy
The amount of energy required to remove an electron from the atom
(how tightly an atom holds on to its electrons)
A general term for the energy required to remove an electron from an orbital in an atom. Think of it also as the energy required to make a cation.
Down a group
ionization energy decreases, because…
Across a period
ionization energy increases, because…

11. Electron Affinity
The electron affinity of an element is the energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion.
The attraction to additional electrons
A fluorine atom in the gas phase, for example, gives off energy when it gains an electron to form a fluoride ion.
Down the group
electron affinity decreases, because
Across the period
electron affinity increases, because

12. Electronegativity
The attraction an atom has for electrons in a covalent bond.
The ability of an atom to attract electrons in a chemical bond.
Down the group
Electronegativity values decrease, because
Across the period
Electronegativity values increase, because
*Noble gases are the exception to this rule.