Chapter 5

1. Chapter 5 Write the notes that are underlined.

2. Valence Electrons • Electrons that are in the highest occupied energy level of an atom • Important to chemical reactions • The reason elements in a group have similar properties

3. Alkali Metals • Group 1A (Li, Na, K, Rb, Cs, Fr) • 1 valence electron • Extremely reactive • Reactivity increases from top to bottom of group

4. Alkaline Earth Metals • Group 2A (Be, Mg, Ca, Sr, Ba, Ra) • 2 valence electrons • Reactivity increases going down the group • Examples: • Magnesium: in chlorophyll (where plants produce energy from sunlight), makes metals stronger • Calcium: in bones for strength

5. Boron Family • Group 3A (B, Al, Ga, In, Tl) • 3 valence electrons • Al is the most abundant metal in Earth’s crust • Recycling Al uses 5% of the energy needed to originally extract it from the Earth

6. Carbon Family • Group 4A (C, Si, Ge, Sn, Pb) • 4 valence electrons • Metallic nature increases down the group • What does that say about conductivity? • Life on Earth is carbon based • Silicon is the 2nd most abundant element in Earth’s crust

7. Nitrogen Family • Group 5A (N, P, As, Sb, Bi) • 5 valence electrons • N and P are found in fertilizers

8. Oxygen Family • Group 6A (O, S, Se, Te, Po) • 6 valence electrons • O is the most abundant element in Earth’s crust

9. Halogens • Group 7A (F, Cl, Br, I, At) • 7 valence electrons • F and Cl are gases • Br evaporates quickly • I sublimes (solid to gas without liquid phase)

10. Noble Gases • Group 8A (He, Ne, Ar, Kr, Xe, Rn) • He has 2 valence electrons • Other 5 have 8 valence electrons • Colorless • Odorless • Extremely un-reactive