The AtomThe AtomElements! Elements! Elements!Elements! Elements! Elements!

ObjectivesObjectives

Atomic StructureThe Atomic Theory and HistoryAtomic Math

Atomic StructureThe Atomic Theory and HistoryAtomic Math

Element QuizzesElement Quizzes

In order to strengthen your familiarity with elements, you will be required to take element quizzes.

In order to strengthen your familiarity with elements, you will be required to take element quizzes.

Element Wanted PosterElement Wanted Poster

To demonstrate you knowledge of the concepts we will cover this six weeks. You will be expected to create a poster containing information about an element in the form of a WANTED poster.

To demonstrate you knowledge of the concepts we will cover this six weeks. You will be expected to create a poster containing information about an element in the form of a WANTED poster.

Atomic StructureAtomic Structure

Atomic Structure Atomic Structure

Atoms are the building blocks of matter.

Atoms make up elements – in fact everything is made of atoms!

There are 92 elements that occur naturally on Earth and about a dozen more that are man-made.

All the elements can be found on the Periodic Table of the Elements.

Atoms are mostly empty space.

Atoms are the building blocks of matter.

Atoms make up elements – in fact everything is made of atoms!

There are 92 elements that occur naturally on Earth and about a dozen more that are man-made.

All the elements can be found on the Periodic Table of the Elements.

Atoms are mostly empty space.

There are two regions in the atom:

There are two regions in the atom:

Nucleus Most of the mass Has a positive

charge Electron Cloud

Most of volume/space

Has a negative charge

Nucleus Most of the mass Has a positive

charge Electron Cloud

Most of volume/space

Has a negative charge

Each region has specific subatomic particles

Each region has specific subatomic particlesNucleusNucleus

Protons p+

Have a positive charge

Mass = 1 amu Discovered by E.

Rutherford

Neutrons n0

Have a neutral or no charge

Mass = 1 amu Discovered by J.

Chadwick

NucleusNucleus Protons p+

Have a positive charge

Mass = 1 amu Discovered by E.

Rutherford

Neutrons n0

Have a neutral or no charge

Mass = 1 amu Discovered by J.

Chadwick

Electron CloudElectron Cloud Electrons e-

Have a negative charge

Mass = 0 amu Discovered by J.J.

Thomson

Electron CloudElectron Cloud Electrons e-

Have a negative charge

Mass = 0 amu Discovered by J.J.

Thomson

Let’s Check for UnderstandingLet’s Check for Understanding

What are the two regions of the atom?

Which one is most of the mass of the atom?

Which one is most of the volume?What are the subatomic particles

and where are they found?

What are the two regions of the atom?

Which one is most of the mass of the atom?

Which one is most of the volume?What are the subatomic particles

and where are they found?

The Atomic Theory and HistoryThe Atomic Theory and History

Democritus and “atomos”Democritus and “atomos”

Democritus was an ancient Greek philosopher (he lived around 400 B.C.) who believed that matter

could not be divided into smaller and smaller pieces forever and ever. He called the smallest

pieces of matter “atomos” which means “indivisible” or

“unbreakable.”

Democritus was an ancient Greek philosopher (he lived around 400 B.C.) who believed that matter

could not be divided into smaller and smaller pieces forever and ever. He called the smallest

pieces of matter “atomos” which means “indivisible” or

“unbreakable.”

John DaltonJohn Dalton

A nineteenth century scientist who also believed that matter was made up of atoms. He coined the term “atom” from the Greek word “atomos.”.

A nineteenth century scientist who also believed that matter was made up of atoms. He coined the term “atom” from the Greek word “atomos.”.

In this first modern atomic theory he stated:

In this first modern atomic theory he stated:

1. Atoms are small, indivisible particles that are the building blocks of matter. (He viewed them as solid spheres.)

2. Atoms can be physically mixed together to form mixtures.

3. Atoms cannot be changed into another element through chemical reactions.

1. Atoms are small, indivisible particles that are the building blocks of matter. (He viewed them as solid spheres.)

2. Atoms can be physically mixed together to form mixtures.

3. Atoms cannot be changed into another element through chemical reactions.

In this first modern atomic theory he stated:

In this first modern atomic theory he stated:

4. Atoms can be combined or rearranged in whole number ratios to form compounds through chemical reactions.

5. All atoms of a particular element are exactly the same; atoms of different elements are different

4. Atoms can be combined or rearranged in whole number ratios to form compounds through chemical reactions.

5. All atoms of a particular element are exactly the same; atoms of different elements are different

Check for UnderstandingCheck for Understanding

What did Democritus believe?Who expanded on Democritus’

beliefs and how?Name the points of the Modern

Atomic Theory.

What did Democritus believe?Who expanded on Democritus’

beliefs and how?Name the points of the Modern

Atomic Theory.

Atomic MathAtomic Math

Let’s ReviewLet’s Review

From previous slides you have learned that all elements/atoms are listed on what?

The Periodic Table of Elements

From previous slides you have learned that all elements/atoms are listed on what?

The Periodic Table of Elements

1

H1.008

Hydrogen

Atomic NumberElement SymbolAtomic MassElement Name

Atomic NumberElement SymbolAtomic MassElement Name

1

H1.008

Hydrogen

Atomic NumberThe whole

number on the chart

Equivalent to the number of protons and electrons if there is no charge.

Atomic NumberThe whole

number on the chart

Equivalent to the number of protons and electrons if there is no charge.

1

H1.008

Hydrogen

Atomic Mass The decimal number

on the chart.Average number of

different masses of naturally occurring isotopes of an element.

Units: may be in grams or atomic mass units (amu)

amu = defined as exactly 1/12th the mass of a carbon-12 atom

Atomic Mass The decimal number

on the chart.Average number of

different masses of naturally occurring isotopes of an element.

Units: may be in grams or atomic mass units (amu)

amu = defined as exactly 1/12th the mass of a carbon-12 atom

1

H1.008

Hydrogen

Mass NumberThe atomic mass

rounded to the nearest whole number.

Equivalent to the number of protons plus the number of neutrons.

Mass NumberThe atomic mass

rounded to the nearest whole number.

Equivalent to the number of protons plus the number of neutrons.

Atomic Math OverviewAtomic Math Overview

# of p+ = Atomic Number# of n = Mass Number - # of p0

# of e- (no charge) = # of p+

# of p+ = Atomic Number# of n = Mass Number - # of p0

# of e- (no charge) = # of p+

Elemental SymbolsElemental Symbols

A- Mass NumberZ- Atomic NumberX- Element Symbol

A- Mass NumberZ- Atomic NumberX- Element SymbolX

A

Z

Fe56

26

Try this one on your ownTry this one on your own

Element

Protons

Neutrons

Electrons

Atomic #

Mass #

Charge

Iron

26

26

56

30

26

How many protons and neutrons are in one atom of 3

7Li?How many protons and neutrons

are in one atom of 74184W?

How many protons and neutrons are in one atom of 3

7Li?How many protons and neutrons

are in one atom of 74184W?

3 protons and 4 neutrons3 protons and 4 neutrons

74 protons and 110 neutrons74 protons and 110 neutrons

IsotopesIsotopes

IsotopesIsotopes

Atoms that have the same number of protons and electrons but different numbers of neutrons

Isotopes have different mass numbers because of the differing numbers of neutrons

Atoms that have the same number of protons and electrons but different numbers of neutrons

Isotopes have different mass numbers because of the differing numbers of neutrons

Isotope names are the atom name and mass number hyphenated

Isotopes with practical uses: carbon-14 ~ archaeological carbon dating americium-241 ~ smoke alarms cobalt-60 ~ treatment of cancer

Isotope names are the atom name and mass number hyphenated

Isotopes with practical uses: carbon-14 ~ archaeological carbon dating americium-241 ~ smoke alarms cobalt-60 ~ treatment of cancer

IsotopesIsotopes

In nature, most elements occurs as a mixture of two or more isotopes.

Each isotope of an element has a fixed mass and a natural percent abundance.

Example: Carbon has two isotopes. Both have 6 protonscarbon-12: six neutrons (C-12)carbon-13: seven neutrons (C-13)

In nature, most elements occurs as a mixture of two or more isotopes.

Each isotope of an element has a fixed mass and a natural percent abundance.

Example: Carbon has two isotopes. Both have 6 protonscarbon-12: six neutrons (C-12)carbon-13: seven neutrons (C-13)

Isotopes & Atomic MassIsotopes & Atomic Mass

Atomic mass of an element is a weighted average of the masses of its isotopes.

You can calculate atomic mass based on relative abundance. You will need the :mass of each isotopenatural percent abundance of each

isotope

Atomic mass of an element is a weighted average of the masses of its isotopes.

You can calculate atomic mass based on relative abundance. You will need the :mass of each isotopenatural percent abundance of each

isotope

Calculating Atomic MassCalculating Atomic Mass

To calculate the atomic mass of an element:Multiply the atomic mass of each

isotope by its abundance expressed as a decimal

Add the results for all isotopes

To calculate the atomic mass of an element:Multiply the atomic mass of each

isotope by its abundance expressed as a decimal

Add the results for all isotopes

ExampleExample

Magnesium occurs in nature in three isotopic forms: atomic mass

Mg-24 (78.70% abundance) 23.985 amuMg-25 (10.13% abundance) 24.986 amuMg-26 (11.17% abundance) 25.983 amu

Calculate the atomic mass of magnesium for these data.

Magnesium occurs in nature in three isotopic forms: atomic mass

Mg-24 (78.70% abundance) 23.985 amuMg-25 (10.13% abundance) 24.986 amuMg-26 (11.17% abundance) 25.983 amu

Calculate the atomic mass of magnesium for these data.

Calculation:Calculation:For Mg-24: 23.985 amu x 0.7870 =

18.88 amuFor Mg-25: 24.986 amu x 0.1013 =

2.531 amuFor Mg-26: 25.983 amu x 0.1117 =

2.902 amuatomic mass = 24.31

amu

For Mg-24: 23.985 amu x 0.7870 = 18.88 amu

For Mg-25: 24.986 amu x 0.1013 = 2.531 amu

For Mg-26: 25.983 amu x 0.1117 = 2.902 amu

atomic mass = 24.31 amu

IonsIons

IonsIons

Atoms are electrically neutral:# protons (+) = # electrons

(-) Atoms may lose or gain electrons when

they react with atoms of other substances. They become electrically charged particles called ions.

Atoms are electrically neutral:# protons (+) = # electrons

(-) Atoms may lose or gain electrons when

they react with atoms of other substances. They become electrically charged particles called ions.

Two Types of IonsTwo Types of Ions

CationsLoss of electrons Now has more protons than electrons

AnionsGain of electronsNow has more electrons than protons

*Denoted by charge in upper right of symbol.

CationsLoss of electrons Now has more protons than electrons

AnionsGain of electronsNow has more electrons than protons

*Denoted by charge in upper right of symbol.

XA Y

Z

A- Mass NumberZ- Atomic NumberY- ChargeX- Element Symbol

Atomic Math Atomic Math

Denoting Ion ChargesDenoting Ion Charges

Ion charges – the sign follows after the number

To calculate ion charges: # protons - #electrons

Example: An atom of lithium loses 2 electrons (lithium normally has 3 e-). It now is an ion with 2 more protons than electrons. (Ion charge: 3 protons – 1 electron = 2+) Overall, this lithium ion has a positive 2 charge. Write this using the elemental symbol:

Li2+

We can now add the atomic number and mass number to the symbol:

7

3Li2+

Atomic Math BreakdownAtomic Math Breakdown

Cheat Chart

# of p+ = Atomic Number# of n = Mass Number - # of p# of e- (no charge) = # of p+

# of e- (w/ charge) = # of p+ - charge

Fe56

3+

26

Atomic Math Atomic Math

Element

Protons

Neutrons

Electrons

Atomic #

Mass #

Charge

Iron

26

26

56

30

+3

23

Practice ProblemsPractice Problems

Fe56

2+

26

Try this one on your ownTry this one on your own

Element

Protons

Neutrons

Electrons

Atomic #

Mass #

Charge

Iron

26

26

56

30

+2

24

How many protons, neutrons, and electrons are in one atom of 3

7Li1+?

How many protons, neutrons, and electrons are in one atom of

74184W3+?

How many protons, neutrons, and electrons are in one atom of 3

7Li1+?

How many protons, neutrons, and electrons are in one atom of

74184W3+?

3 protons 4 neutrons 2 electrons3 protons 4 neutrons 2 electrons

74 protons 110 neutrons 71 electrons74 protons 110 neutrons 71 electrons

Make up your own problem for each format used.

Then give it to your neighbor or Ms. Adams to try

Make up your own problem for each format used.

Then give it to your neighbor or Ms. Adams to try