Elements # of Protons # of neutrons # of electrons Mass # Atomic Lithium #1. 3 #2. 4 #3. 3 #4. 7 #5. 3 Carbon #6. 6 #7. 6 #8. 6 12 6 Chlorine 17 19 36 Silver 47 61 108 lead 82 125 207

Ch.12 Section 2 Grouping the Elements Explain why elements in a group often have similar properties Describe the properties of the elements in the groups of the periodic table

Periods As you move from left to right across a row, the elements become less metallic

Group 1: Alkali Metals Are the most reactive metals Have one outer energy level electron Pure alkali metals are stored in oil to keep them from reacting with water and oxygen in the air. Only found in nature combined with other elements Like table salt (sodium chloride)

Group 2: Alkaline-Earth Metals Very reactive but less reactive than group 1 Have 2 electrons in the outer energy level Calcium is found in cement, chalk, and your bones and teeth.

Group 3-12: Transition Metals Are less reactive than group 1 or 2 Examples being passed around are Zinc and Copper Properties Shiny Malleable- can be hit with a hammer and not shatter Can conduct electricity Can conduct thermal energy

Lanthanides and Actinides They are from periods 6 and 7 They are found at the bottom of the periodic table Lanthanides are used to make steel Actinides are radioactive because they are “unstable”

Group 13: Boron Has 3 electrons in the outer energy level Reactive The most common element in group 13 is aluminum (the most abundant metal in the Earth’s crust)

Group 14: Carbon Group Has 4 electrons in the outer energy level Carbon forms compounds such as proteins, fats, and carbohydrates which are important to your diet. Diamonds and Coal have very different properties, yet both are natural forms of carbon Silicon and germanium are used to make computer chips

Group 15: Nitrogen Group Have 5 electrons in their outer energy level Nitrogen is a gas at room temperature and makes up 80% of the air you breathe.

Group 16: Oxygen Group Has six electrons in the outer energy level Oxygen is also a gas at room temp and only makes up 20% of air. Oxygen is necessary for substances to burn.

Group 17: Halogens Has 7 electrons in the outer energy level They are VERY reactive NONMetals because their atoms only need to gain one electron to have a complete outer level ( 7+1=8 and 8 is the most you can have!) Chlorine and Iodine are examples of Halogens

Group 18: Noble Gases Have 8 electrons in the outer energy level They are Unreactive nonmetals. Helium is a noble gas that’s low density allows it to float

Hydrogen The properties of H do not match the properties of any single group, so H is set apart from other elements on the periodic table. H has only 1 electron, thus they have 1 electron in the outer energy level H is the MOST ABUNDANT element in the universe It is a colorless and odorless gas