1. Unit 2 Chemistry

2. Atomic Mass and Isotopes While most atoms have the same number of protons and neutrons, some don’t. Some atoms have more or less neutrons than protons. These are called isotopes. An atomic mass number with a decimal is the total of the number of protons plus the average number of neutrons. We write isotopes like this: Uranium has 2 isotopes: Uranium – 238 & Uranium - 239 U 238 92 Mass # Atomic # U 239 92

3. Isotope Examples List the protons, neutrons, electrons and the symbol Carbon – 12 Carbon – 13 Carbon – 14 Note:  The # of neutrons may vary.  Isotopes have different mass numbers.  Isotopes of the same element are still chemically alike because they have the same number of protons and electrons.

5. Properties of Metals Metals are good conductors of heat and electricity. Metals are shiny. Metals are ductile (can be stretched). Metals are malleable (can be pounded into thin sheets). A chemical property of metal is its reaction with water which results in corrosion.

6. Properties of Non-Metals Non-metals are poor conductors of heat and electricity. Non-metals are not ductile or malleable. Solid non-metals are brittle and break easily. They are dull (not shiny). Many non-metals are gases. Sulfur

7. Properties of Metalloids Metalloids (metal-like) have properties of both metals and non-metals. They are solids that can be shiny or dull. They conduct heat and electricity better than non- metals but not as well as metals. They are brittle and not ductile Silicon

8. A Family is also called a Group.

9. based on their atomic numbers.

10. Groups or Families Columns of elements are called groups or families. Columns of elements are called groups or families. Elements in each family have similar but not identical properties. Elements in each family have similar but not identical properties. All elements in a family have the same number of valence electrons. All elements in a family have the same number of valence electrons. Each horizontal row of elements is called a period. Each horizontal row of elements is called a period. The elements in a period are not alike in properties. The elements in a period are not alike in properties. In fact, the properties change greatly across even given row. In fact, the properties change greatly across even given row. The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas. The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas. The period tells us how many orbitals the element has. The period tells us how many orbitals the element has. Periods

11. Groups of the Periodic Table Alkali Metals: Group 1 Alkali Metals: Group 1 Soft, shiny metals Soft, shiny metals Good conducters Good conducters Very reactive Very reactive Will produce a coloured flame when heated Will produce a coloured flame when heated Excluding H – a diatomic molecule Excluding H – a diatomic molecule Li - lithium Rb - rubidium Li - lithium Rb - rubidium Na – sodiumCs - caesium Na – sodiumCs - caesium K - potassium Fr – francium K - potassium Fr – francium

12. Groups Alkaline Earth Metals – group 2 Alkaline Earth Metals – group 2 Have 2 valence electrons Have 2 valence electrons Most are white in colour Most are white in colour Be – beryllium Be – beryllium Mg – magnesium Mg – magnesium Ca – calcium Ca – calcium Sr – strontium Sr – strontium Ba – barium Ba – barium Ra – radium (not always considered an alkaline earth due to its radioactivity) Ra – radium (not always considered an alkaline earth due to its radioactivity)

13. Groups Group 3 - 12: Transition Elements Elements that have an incomplete subshell Group 13: Boron Group These elements are characterized by having 3 electrons in the outer energy level (valence) Group 14: Carbon Group These elements are characterized by having 4 electrons in the outer energy level these elements share their electrons, the tendency to lose electrons increases as the size of the atom increases, as it does with increasing atomic number

14. groups Group 15 Nitrogen group Group 15 Nitrogen group These elements are characterized by having 5 electrons in the outer energy level (valence) These elements are characterized by having 5 electrons in the outer energy level (valence) Group 16 Oxygen group) Group 16 Oxygen group) These elements are characterized by having 6 electrons in the outer energy level (valence) These elements are characterized by having 6 electrons in the outer energy level (valence) Group 17 Halogens Group 17 Halogens The term halogen was coined to mean elements which produce a salt in union with a metal The term halogen was coined to mean elements which produce a salt in union with a metal The elements are characterized by having 7 electrons in the outer energy level (require 1 more electron) The elements are characterized by having 7 electrons in the outer energy level (require 1 more electron)

15. Noble Gases Noble Gases are colorless gases that are extremely un-reactive. One important property of the noble gases is their inactivity. They are inactive because their outermost energy level is full. Because they do not readily combine with other elements to form compounds, the noble gases are called inert. The family of noble gases includes helium, neon, argon, krypton, xenon, and radon. All the noble gases are found in small amounts in the earth's atmosphere.

16. Assignment Families of the Periodic Table worksheet Families of the Periodic Table worksheet In computer lab