Unit 1 Test Reminder A Unit 1 Practice Test, self-evaluation sheet, and a review sheet have been posted on Sharepoint. Please read through the review sheet carefully; most of your questions will be answered there.

Warmup (5 minutes) Silicon has three stable isotopes in nature as shown below. Find the missing information. Mass of Silicon Isotope% Abundance of Si Isotope av.atm.ma Si = (27.98)(0.9221) x + (29.97)(0.0309) = x = x x = amu x

The Periodic Table and Electron Diagrams A chemistry student wished to make some potassium hydroxide solution and decided to throw a large lump of potassium into a bucket of water. Her professor observed what she was about to do, out of the corner of his eye and hurried towards her. After confirming this was what she was intending to do, he asked her first to stir the water in the bucket for five minutes before adding the potassium. She was puzzled and ran after him to ask the purpose of this action. “It will give me time to get away” said the professor. Today you need paper for notes, your PT and maybe some colors….

Periodic Table Development n In the mid 1800’s there was no organization of the known handful of elements. It was difficult to find information, and chemistry didn’t make sense. n In 1869, Dimitri Mendeleev arranged the elements in rows according to increasing atomic mass and in columns according to the way they reacted n In 1913, Henry Moseley filled in the blank spaces, and revised the PT based on atomic number I’m the MAN! I’m pretty studly myself!

Stowe Periodic Table

A Spiral Periodic Table

How many *groups *periods are there? *period/series: horizontal row; as you move left or right, properties of the element change group/family: vertical column; elements share many of the same physical and chemical properties

2 1 3 – 12 or B group metals Look carefully at the 2 ways that the groups on your PT is numbered

Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87 Group IA soft, shiny, very reactive with water and air *hydrogen is not part of this group I

Be Ra Mg Ca Sr Ba Group IIA *reactive, but less reactive than alkali *harder, more dense *always combined with nonmetals in nature * many are important mineral nutrients

Transition metals: The bling bling metals Lanthanides Actinides Bi Sn Al Ga  Less reactive, hard metals  Jewelry/construction.  Metals used “as metal.”

Metals are:  Good conductors of heat and electricity  Malleable (easily flattened)  Ductile (can stretch it into a thin wire)  Have luster (shiny)  Silvery  Use a marker to OUTLINE the metals

Metalloids or Semimetals Have properties of both metals & nonmetals B At Color in the semimetals, outline the nonmetals as one large unit for right now (do not color)

Metals vs. Nonmetals vs. Metalloids Metal Metalloid (Semimetal) Nonmetal Good conductors of electricity and heat Okay conductors of electricity and heat. Poor conductors of electricity and heat Shiny (luster) Can look shiny or dull. Not Shiny Malleable Can be malleable or brittle. Not Malleable (brittle) Most are SOLID at room temp. All are SOLID at room temp. Most are GAS at room temp.

Group VIIA Br I I Cl F F n mostly colored & gaseous n very reactive, combine with metals to form salts

Group VIIIA Ar Kr Xe Ne He Rn n do not react n gaseous

Periodic Table Groups Metals Alkali Metals Alkaline Earth Metals Transition Metals SemimetalsNonmetals HalogensNoble GasesOther (Family) C, N, O P, S, Se, H

The Periodic Table and Valence Electrons n Remember that Mendeleev grouped elements according to similar chemical and physical properties! n What CAUSES some elements to have similar chemical properties? Same number of valence electrons, same kinds of ions, similar reactivity. But what is a valance electron, how are they different than ‘regular’ e-, and how do I know how many an atom has?

What are valence electrons? n electrons found in the outermost energy shell. n only valence e- interact with other atoms in chemical reactions (inner e- are shielded) n only the raincoat gets wet; your sweater, and shirt stay dry. Valence Shell

Bohr Electron Diagrams - technically NOT entirely accurate. - improved upon with the addition of more information - but since it is easier to learn from…we will use this model to understand how electrons work!

1 st shell: holds 2 e- 2 nd shell: holds up to 8 e- 3 rd shell: holds up to 8 e- **Other shells (energy levels) hold more electrons, we won’t get into this! e- e- are restricted to energy levels around a nucleus. This is the e- arrangement of WHICH neutral element? Ar, group 8A

Beryllium – 9 4 P 5 N e- Steps: Bohr Electron Diagrams 1. How many protons and neutrons? 2. How many electrons? (assume neutral). 3. Filling first energy shell…maximum two e- 4. If needed, fill out the second energy shell. Space apart the first 4 e-, then pair them up. In which group is this element?

Carbon – 12 6 P 6 N e- In which group is this element?

Fluorine – 19 9 P 10 N e- In which group is this element?

valence electron (Lewis dot) diagrams Ex. Lithium P 3 N e- Li In which group is this element?

Aluminum P 14 N e- Al In which group is this element?