3.00_Chemistry of Biology

Biology I

Periodic Table of the Elements

Slides 33-44 1 Organizing Elements (Patterns) The of Elements is a way of organizing the elements in relation to each other so it is easy to find elements that have similar properties.

2 Periodic Table of the Elements How do you read the PERIODIC TABLE?

3 Mass Number

4 Periods Each row is called a “” The elements in each period have the same number of electron shells

Hint: A period comes at the end of a sentence--a horizontal line. 5 www.chem4kids.com Periods (Rows) Properties Seven periods on a periodic table (numbered from the top down)

Atomic numbers and atomic masses increase as you move from the left to the right in a period

All atoms of the elements in the same period have the same number of orbitals/levels

All atoms of the elements in a specific period have that respective number of orbitals/levels

6 Periods The horizontal rows of the periodic table are called periods.

Elements in a period are not alike in properties. The first element in a period is usually an active solid, and the last element in a period is always an inactive gas.

7 Periods Rows Atomic size (number of protons) decreases from left to right across a period.

Atomic mass (number of protons) increases from left to right across a period.

8 Periods Rows are on the left

Non-metals are on the right

9 Groups or Families 1 = 1 electron Group 8 = 8 electrons Group 2 = 2 electrons Except for He, it has 2 electrons Each column is called a “group” or family.

Each element in a group has the same number of electrons in its outer orbital, also known as its outer shell. The electrons in the outer shell are called “valence electrons.” Hint: Your Family tree is vertical. 10 www.chem4kids.com Groups or Families • The vertical (up and down) columns of the periodic table (there are 18) are called groups or families.

• Elements in the same group or family have similar characteristics or properties.

11 Groups Names

Group 1: Alkali metals Group 2: Alkaline earth metals Group 3-11 : Transition Metals Group 11: Coinage metals/ Family Group 12-14: & Group 15: /Nitrogen Family Group 16: /Oxygen Family Group 17: /Halide Family Group 18: Noble gases 12 Periodic Table of the Elements

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