Atoms and the Periodic Table of Elements

January, 2012

Atoms

Nucleus

Center of the Atom

Protons and Neutrons Found Here

Contains Almost ALL of the Atom’s Mass

Electron Cloud

Area Around the Nucleus where the Electrons are Found

Atoms…Continued

Nucleus

Protons + Neutrons

Electron CloudBlurry Area Containing

Electrons

Atoms…Relative Size One dust particle has millions of atoms

100 million million billion hydrogen atoms are in a regular size balloon

Twenty thousand billion billion atoms are in a nickel

Imagine 1 grain of rice is one electron. 2,000 grains of rice represent a proton.

Imagine that an electron is as big as a grain of sand. Then the nucleus of an atom would be as big as a marble. The electron cloud would have a radius of 25 meters!

If we could magnify the simplest hydrogen atom to the size of the earth, then the nucleus (a proton) would only be about the size of a basketball. It would be at the very center of the earth and that lonely electron would be found somewhere out in earth's atmosphere. All of the space in between the electron and the basketball-size nucleus is empty!

Atoms…Relative Size…Continued

Subatomic Particles Proton

Positive “1” Charge

Mass of “1”

Found in Nucleus

Determines the ELEMENT (3P = Li; 30P = Zn)

Neutron

Neutral or Zero Charge

Mass of “1”

Found in Nucleus

Electron

Negative “1” Charge

Very Little “0” Mass

Found in Electron Cloud Surrounding Nucleus

Subatomic Particles…Continued

Atom Variations Isotopes

Atoms of the SAME ELEMENT with a Different (+ or -) number of NEUTRONS

ONLY the Atomic Mass changes

Read and Written as “Carbon-14” or “Uranium-236”

Ions

An Atom or Molecule that has a Different Number of Electrons than Protons

Adding Electrons Creates a NEGATIVE ion

Subtracting Electrons Creates a POSITIVE ion

The Periodic Table

Method of organization

Dmitri Mendeleev 1869 Predicted the properties of elements and

predicted the discovery of other elements based on the trends in the table.

Based on atomic mass.

Moseley discovered that a more appropriate basis was atomic number.

Periodic Law—When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern.

The Periodic Table Periodic

Occurring or Recurring at Regular Intervals

Columns are called “Groups”

Rows are called “Periods”

Elements are Arranged in Many Ways on the Periodic Table

Similar Properties

Reactivity

Atomic Size

Density

Etc…

Trends Size of Atoms

Decreases from LEFT to RIGHT and Increases from TOP to BOTTOM

Largest: Cesium

Smallest: Helium

Trends…continued

Density

Increases from TOP to BOTTOM

Increases from the OUTSIDE INWARD

Hydrogen: 0.00009 g/cm3

Osmium: 22.57 g/cm3

Melting and Boiling Points decrease as you move down a group and increase as you move left to right across a period.

On Your Periodic Table, Add:

1

3

4

4 5 6 1110987 12

13 15 16 17

18

14

5

3

1

2

6

7

2

AlkaliMetals

AlkalineEarthMetals

TransitionMetals

BoronGroup

CarbonGroup

NitrogenGroup

OxygenGroup

Halogens

NobleGases

Metals & Nonmetals Metals (left of zig-

zag line)

Luster/shine

Good conductors of heat and electricity.

Malleable (hammered or rolled into sheets)

Ductile (stretched or drawn into wires)

All are solids except for Mercury

Nonmetals (right of zig-zag line)

No luster

Poor conductors

Not malleable or ductile

Many are gases; Bromine is a liquid; some are solids

Metalloids

Metalloids ( 7 Eelements ALONG zig-zag line)

Called semi-metals

Have properties of BOTH metals and nonmetals

Example – Silicon

Shiny

Brittle

Poor electrical conductor

Example – Boron

Acts as a metal when reacting with Fluorine

Acts as a nonmetal when reacting with Sodium

Element “Boxes”Atomic Number

Determines Element= Protons

= Electrons

Atomic Symbol1 or 2 Letters

1st is Capitalized2nd is NOT

Atomic or ElementName

Atomic Mass= Protons + Neutrons

Atomic Math!# Protons = _____ (Same as Atomic Number)

# Electrons = _____ (Same as Atomic Number)

# Neutrons = _____ (Rounded Atomic Mass MINUS Atomic Number)

# Protons = ____

# Electrons = _____

# Neutrons = _____

99

99

153

52

41

41

Group 1: Alkali Metals 1 Valence Electron

Never found in elemental form in nature

Very Reactive

Stored under oil

Silver in Color

Soft

Form “Salts” with Halogens K

Group 2: Alkaline Earth Metals

2 Valence Electrons

Moderately Reactive

Silver in Color

Soft Mg

Groups 3-12: Transition Metals

All “useful” metals

Random properties and electron configurations

Group 13: Boron Group

3 Valence Electrons

Ga

Group 14: Carbon Group

4 Valence Electrons

C

Group 15: Nitrogen Group

5 Valence Electrons

Moderately Reactive

Some VERY TOXIC (P, As, Sb)

P

Group 16: Oxygen Group

6 Valence Electrons

Moderately Reactive

Te

Group 17: Halogens7 Valence Electrons

Very Reactive

All form Acids with Hydrogen

Forms “salts” with Alkali Metals At

Group 18: Noble Gases

8 Valence Electrons (*2 for Helium)

Full Valence Shells

Non Reactive (Inert)Kr

“QUIZ” (Extra Flap in Flip Book)

Study Information for Each Group!

Name

# Valence Electrons (except groups 3-12)

Lewis Dot Structure (Element Symbol is Given)

Facts

Group 1: 3 Facts

Group 2: 2 Facts

Groups 3-12: 1 Fact

Group 15: 1 Fact

Group 16: 1 Fact

Group 17: 2 Facts

Group 18: 2 Facts