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

27.98

4.70

29.97 3.09

av.atm.ma Si = (27.98)(0.9221) + 0.0470x + (29.97)(0.0309)

28.09 = 25.800358 + 0.0470x + 0.92607

1.36357 = 0.0470x

x = 29.01 amu

x92.21 0.9221

0.04700.0309

The Periodic Table and Electron Diagrams

A chemistry student wished to make some potassiumhydroxide 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 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.

In 1869, Dimitri Mendeleev arranged the elements in rows according to increasing atomic mass and in columns according to the way they reacted

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 TableStowe Periodic Table

A Spiral Periodic TableA Spiral Periodic Table

G

R

P E R I O D O

U

P

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

IA VIIIA

IIA IIIA IVA VA VIA VIIA

2

1

3 – 12 or B group metals

13 14 15 16 17

18

Look carefully at the 2 ways that the groups on your PT is numbered

Li3

Na11

K19

Rb37

Cs55

Fr87

Group IAsoft, shiny, very

reactive with water and air

*hydrogen is not part of this group

I

BeBe

RaRa

MgMg

CaCa

SrSr

BaBa

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 SemimetalsHave 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

MetalMetalloid

(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

MalleableCan 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 Br

I I

Cl Cl

F F

mostly colored & gaseousvery reactive, combine with metals to form salts

Group VIIIA

Ar Ar

Kr Kr

Xe Xe

Ne Ne

He He

Rn

Rn

do not reactgaseous

Periodic TableGroups

Semimetals NonmetalsMetals

Alkali MetalsAlkaline Earth

MetalsTransition

MetalsHalogens Noble Gases Other

(Family)

C, N, O P, S, Se, H

The Periodic Table and Valence Electrons

Remember that Mendeleev grouped elements according to similar chemical and physical properties!

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?

electrons found in the outermost energy shell.

only valence e- interact with other atoms in chemical reactions (inner e- are shielded)

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!

1st shell: holds 2 e-

2nd shell: holds up to 8 e-

3rd shell: holds up to 8 e-

**Other shells (energy levels) hold more electrons, we won’t get into this!

e-

e-

e-e-

e-

e-

e-e-

e-e-

e-

e-e-

e-e-

e-

e-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 P5 N

e-

e-

e-

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 P6 N

e-

e-e-

e-

e-

e-In which

group is this element?

Fluorine – 19

9 P10 N

e-

e-e-

e-

e-

e-

e-

e-

e-

In which group is this

element?

valence electron (Lewis dot) diagrams

Ex. Lithium - 6

3 P3 N

e-

e-e- Li

In which group is this

element?

Aluminum - 27

13 P14 N

e-

e- e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e- Al

In which group is this

element?