Chapter 1 Activity 7: How Electrons Determine Chemical Behavior

Bohr Model—shows the electrons in various energy levels How many electrons can fit into each energy level?????? Max # e- = 2n2 where n= energy level Ex. If n=1 (1st energy level), then 2(1)2= Ex. If n=2 (2nd energy level), then 2(2)2= Ex. If n=3 (3rd energy level), then 2(3)2=

Valence Electrons Valence electrons Electrons in the outermost energy level of an atom

Valence Electrons The Group Number tells us the # of

Valence Electrons The Group Number tells us the # of Valence e- stays the same down a group Valence e- increases across a period

Valence Electrons How many valence electrons does a Fluorine atom have? a Magnesium atom have? an element in the noble gas family have?

Things You Need to Now Know On the periodic table: The COLUMN or GROUP or FAMILY equals the # of valence electrons (for columns 1,2, 13-18) The ROW or PERIOD equals the energy level

Bohr Models Rutherford focused on describing the nucleus Bohr focused on describing the location of the electrons Bohr model (planetary model): -shows electrons moving in orbits (energy levels) around the positive nucleus of the atom.

Bohr model for Hydrogen                                                                                                                                                  Hydrogen is in period 1 = 1st energy level Hydrogen is the first box in period 1 = 1 electron Energy level 1 1H 1 # of Electrons in that Energy level

Bohr model for Lithium 3Li 2 1                                                                                                                                                    Lithium is in period 2 = 2nd energy level Lithium is the first box in period 2 = 1 electron Energy level 1 3Li 2 1 Energy level 2 # of Electrons in 2nd Energy level # of Electrons in 1st Energy level

Using What You Now Know Duet Rule: In forming compounds, atoms tend to gain or lose electrons in order to have two electrons in their first energy level. Octet Rule: In forming compounds, atoms tend to gain or lose electrons in order to have eight electrons in their outer energy level.

Stability                                                                                                                                                    Atoms will lose or gain electrons to have a filled outer energy level (duet rule or octet rule). This fluorine atom has only 7 valence electrons The octet rule isn’t satisfied 9F 2 7

Stability -1 -1 A fluorine atom will try and gain an electron (7e- + 1e- = 8e-). With 8e-s, it is now an ANION (-1) with 8 valence electrons The anion now obeys the octet rule. -1 9F 2 8

Stability This sodium atom has 1 valence electron. The octet rule isn’t satisfied. 11Na 2 8 1

Stability If the sodium atom loses it’s valence electron, it will now have 8 valence electrons. The octet rule is satisfied. +1 11Na 2 8

Why Atoms React -nonmetals want to keep their valence electrons Some atoms want to lose valence electrons more than others -nonmetals want to keep their valence electrons -metals want to lose their valence electrons

Why Atoms React nonmetals want to keep their valence electrons metals want to lose their valence electrons