Ions

LG: I can explain how atoms form ions and write ion symbols for the

first 20 elements

Ions• What is an ion?

– An ion is an atom that has lost or gained electrons– If an atoms loses electrons it has a positive charge– If an atoms gains electrons it has a negative charge

• Why do ions form?– Atoms gain or lose electrons to get a full valence shell…to become

STABLE

• How do you know if an atom will gain or lose electrons to form an ion?– Atoms will GAIN electrons if their valence shell is mostly FULL– Atoms will LOSE electrons if their valence shell is mostly EMPTY

How Atoms Form IonsElement Sodium Oxygen

Bohr-Rutherford Diagram

Gain or Lose e-

Charge

Ion symbol

Practice• Complete Bohr-Rutherford Diagrams for elements

11-20 (yesterday’s handout)• By looking at the valence electrons, decide whether

each atom would gain or lose electrons, and how many, to form an ion

• In the empty space at the bottom of the handout:– Write ion symbols for the first 20 elements– Explain what the elements in the same column have in

common– What is special about Carbon and Silicon?

The Periodic Table!

LG: I can describe the location and properties of chemical families

Modern Periodic Table

• Established by Dmitri Mendeleev in 1871• He grouped elements with similar physical and

chemical properties• These groups are called FAMILIES• Elements are also divided into two big groups:

Metals and Non Metals

Periodic Table Organization

• Metals are on the left and nonmetals on the right

Chemical Families• Alkali Metals - Group 1– Soft, shiny, react with water, form +1 ions

Chemical Families• Alkaline Earth Metals – Group 2– Somewhat soft, some are shiny, react with water, form +2 ions

Chemical Families

• Halogens – Group 17– Gases/liquids/solids, nonmetals, very reactive,

form -1 ions

Chemical Families

• Noble Gases - Group 18– All gases, un-reactive (full valence shell)

Chemical Families

• Metalloids - Staircase– Some properties of metals and some properties of

nonmetals