3.00_Chemistry of Biology Biology I Periodic Table of the Elements Slides 33-44 1 Organizing Elements (Patterns) The Periodic Table 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 “period” 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 Metals are on the left Non-metals are on the right 9 Groups or Families Group 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/Copper Family Group 12-14: Metalloids & nonmetals Group 15: Pnictogens /Nitrogen Family Group 16: Chalcogens /Oxygen Family Group 17: Halogens /Halide Family Group 18: Noble gases 12 Periodic Table of the Elements 13 .