Work silently. Raise hand to ask Ms. Hughes anything. Do now Work silently. Raise hand to ask Ms. Hughes anything. Draw bohr model for K Draw bohr model for C

Announcements Unit 3 test this Friday If you have not taken 2 chemistry tests yet this semester, see me after to arrange a make up Also, come in for quick tutoring, then RETAKE GLEs for a GRADE BOOST

Mystery Element When it reacts with Oxygen it is called rust. Last year a movie came out called _ _ _ _man. If you don’t have enough of this, you may have anemia. Did it today because we didn’t have much time bc of the mentoes and coke. Did not like that.

Today! Learn an easier way to draw atoms than Bohr Models.

Bohr Models of Atoms (1913) Depict an atom as a small, positively charged nucleus surrounded by electrons that travel in circular energy levels (aka orbitals) around nucleus 16 p+ 16 no Sulfur: 16 protons 16 neutrons 16 electrons

Steps to Making a Bohr Model Figure out how many protons, neutrons, and electrons are in the atom Draw the nucleus (circle) with # p+ and # no inside Draw the first energy level (circle around nucleus) and draw up to 2 dots (electrons) If needed, draw second energy level (second circle) and draw up to 8 dots (electrons) If needed, draw third energy level (third circle) and draw up to 18 dots (electrons) If needed, draw fourth energy level (fourth circle) and draw up to 32 dots (electrons) Continue drawing energy levels as needed (draw up to 32 dots on each)

Energy Levels Where the electrons live!!! Level 1: holds 2

Valence Electrons Valence electrons: the electrons in the outside energy level - ALL TOGETHER, SODIUM HAS 11 ELECTRONS. How many valence electrons does sodium have? - - - - - P=11 N=12 - - - NUCLEUS - -

How many valence electrons in sodium?

How many valence electrons in neon?

How many valence electrons in boron?

How many valence electrons in carbon?

Lewis Dot Structures C The chemical symbol goes in the middle Represents the nucleus and inner energy levels The valence electrons go on the outside What do we notice about Carbon’s Lewis Dot Structure?

C - - - - - - P=6 N=6 The chemical symbol goes in the middle Represents the nucleus and inner energy levels The valence electrons go on the outside -

Electrons only pair up when they have to

C - - - - - - P=6 N=6 The chemical symbol goes in the middle Represents the nucleus and inner energy levels The valence electrons go on the outside -

I DO: Draw the Lewis Dot structure for fluorine

Draw the Lewis Dot structure for hydrogen

WE DO: Draw the Lewis Dot structure for helium

Electrons only pair up when they have to Level 1 holds how many electrons??? 2 So, Helium’s dot structure has paired electrons because they have to

Draw the Lewis Dot structure for nitrogen

Draw the Lewis Dot structure for silicon

YOU DO: Draw the Lewis Dot structure for beryllium

Draw the Lewis Dot structure for carbon

Draw the Lewis Dot structure for oxygen

Draw the Lewis Dot structure for calcium

To Ms. H: Lewis dot structures for elements with atomic number 1-18

The Rule What is “the rule” for valence electrons? There is a pattern Can you find it??? Shhh, don’t say what it is Let everyone get a chance to figure it out for themselves

Background for The Rule Periodic table has columns There are eight main columns (the tall ones) Can we find the 8 tall columns? We can assign numbers 1-8 to the eight tall columns

The Valence Electron Rule For the 8 tall columns, # of valence electrons = column # !!!Wow!!! Now for ALL elements in those 8 columns we know the # of valence electrons

Rapid Fire!!! Li Ca B N O Ar K Be S Al P

Exit Slip What are valence electrons? What’s the rule for valence electrons? Hw: Draw Lewis Dot structures for Xe, Sr, Sb, I, Se, Rb, Ge, Ga Top ten: how’d we do?