Warm Up 1.What evidence did Bohr use for his model? 2.What evidence did Schrodinger use for his model?

Take 1

Next Playa! Bohr Experiment: Hydrogen Emission Spectrum –Hydrogen emits only specific wavelengths of light when it gives off energy Result: –Light is a wave and a particle –Light has different energies –When atoms lose energy they lose it in definite amounts (aka quanta)

Hydrogen Emission Spectrum

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 n o Sulfur: 16 protons 16 neutrons 16 electrons

Bohr: Energy Levels Energy levels: paths around the nucleus that electrons travel Electrons can ONLY exist in those energy levels, NEVER between Energy levels are also known as orbitals When you add energy to an atom the electrons jump to a higher energy level (excited state) –When that electron loses energy and falls back down to its original orbital (ground state) you get light (energy released)

New Notes!

Chemical Reactions Situation where atoms rearrange to make new substances.

Reactants BEFORE What you start with. What reacts or rearranges

Reactants Products BEFORE What you start with. What reacts or rearranges AFTER What you end with. What is produced.

How do you know a reaction happened? EvidenceExample temperature change color change precipitate forms gas released smell

What can happen in a chemical reaction? Old bonds between atoms are broken New bonds between atoms are formed Matter is CONSERVED!

Review- Types of Reactions Synthesis: A + B -> AB Decomposition: AB -> A + B Single Replacement: AB + C -> AC + B Double Replacement: AB + CD -> AD + CB

Double Replacement How to predict products? –Just switch partners –Cations (positive ions) still come first in the formula –Anions (negative ions) still come last in the formula –Polyatomic ions move as a unit –Example?

Practice Double Replacement (aka partner switch!) What forms from: 1.Calcium sulfide and magnesium oxide 2.Potassium chloride and hydrogen carbonate 3.Sodium hydroxide and lithium bromide

Practice Double Replacement (aka partner switch!) What forms from: 1.NaCl and LiF 2.CaO and MgS 3.MgCl 2 and CaI 2 4.CaF 2 and Li 2 O

How to find the charge? Charges of polyatomic ions are on the back of your periodic table Elements in columns 1A-8A follow a pattern: Column1A2A3A4A5A6A7A8A Charge /+4-3-2No ion

Why those charges? Review electron loss/gain

Practice by writing the charge of each element or polyatomic ion CO 3 OH SO 4 B C N Na Be F S

Practice by writing the correct subscripts for the formulas MgF CaO NaN BCl LiS MgN AlO

Remastery quiz Work silently and alone for full credit

Sum Up Top ten: how’d we do? What did we learn today?