Atomic Structure

Do you know your atomic structure?

Basic Unit of Matter

•ATOM• Sodium Atom Animation

What is the charge of each subatomic particle?

• Proton neutron electron

• + O -• positive none negative

Where are they found in the atom?

Neutron and proton – in the nucleus

Electron –outside the nucleus

Helium atom animation

Chemical Element

• A pure substance that consists on only one type of atom

Pure Substance: Iodine

Atom

• EX: every atom in a gold block looks like all the other gold atoms

Periodic Table of the Elements

Mendeleev

Element Song(link)

“The Elements” by Tom Lehrer

• There’s antimony, arsenic, aluminum, selenium,And hydrogen and oxygen and nitrogen and rheniumAnd nickel, neodymium, neptunium, germanium,And iron, americium, ruthenium, uranium,Europium, zirconium, lutetium, vanadiumAnd lanthanum and osmium and astatine and radiumAnd gold, protactinium and indium and galliumAnd iodine and thorium and thulium and thallium.

• There’s yttrium, ytterbium, actinium, rubidiumAnd boron, gadolinium, niobium, iridiumAnd strontium and silicon and silver and samarium,And bismuth, bromine, lithium, beryllium and barium.

• There’s holmium and helium and hafnium and erbium

• And phosphorous and francium and fluorine and terbiumAnd manganese and mercury, molybdinum, magnesium,Dysprosium and scandium and cerium and cesiumAnd lead, praseodymium, platinum, plutonium,Palladium, promethium, potassium, polonium,Tantalum, technetium, titanium, tellurium,And cadmium and calcium and chromium and curium.

• There’s sulfur, californium and fermium, berkeliumAnd also mendelevium, einsteinium and nobeliumAnd argon, krypton, neon, radon, xenon, zinc and rhodiumAnd chlorine, cobalt, carbon, copper,Tungsten, tin and sodium.

• These are the only ones of which the news has come to Harvard,And there may be many others but they haven’t been discovered.

Symbols of Elements

• 1. First letter is capitalized• 2. Second letter (if there is one) is

always lower case• EXAMPLES:• C F Al• Cl B Mn• Ca H Mg• Cr O Mo

Which are symbols?Abbreviations for elements

• C CO Mn CO2 Ni Why?

•C Mn Ni

• Only one capital letter

Trace Elements

Needed by some organisms but only in very small amountsLike iodine, we need only 0.15 mg per dayA deficiency will cause a goiter

What are trace elements?

• Needed in the body in only small amounts

• Like mg (milligrams)• WHY IMPORTANT IF WE DON’T

NEED SO MUCH?• Minerals act as catalysts (speed up

reactions) for many biological reactions

EACH ELEMENT: All the same atoms

• Photographic Periodic Table (link)

Which are elements?

• Cu• C• CO• Co• N• NO• WHY?• Cu C N only

one kind of matter

Atomic Number

• Number of protons of an element

Mass Number

• Protons plus neutrons

• Decimal number

• Will round off the number

• Average of masses of many atoms

Mass Number

• Mass of nucleus

What about that decimal for mass number?

= Average of all isotopes of carbon

• Mass Number • Atomic Number

What is the mass number of Na?

Atomic Number?Mass Number?

HOW TO FIND

• Number of Protons = Atomic Number

• Number of Electrons = Number of Protons = Atomic Number

• Number of Neutrons = Mass Number - Atomic Number

How many?

• Protons electrons neutrons

• Carbon

6 6 6• Chlorine

• 17 17 18

What’s a neutral atom?

• Number of protons = number of electrons

• Example: carbon has 6 e-and 6 p+

Is this a neutral atom?

= p

= e-

Same Number of electrons as protons

• WHY?

• So the atom will be neutral (no excess charge)

What is the mass number of…?

• Carbon nitrogen hydrogen

• WHY?

• 12 14 1

• Decimal number on periodic table

• Not other number in succession

• Number of p + n

What is the atomic number of?

• Silicon fluorine sodium WHY?

• 14 9 11• Number in succession (not

a decimal)• Number of protons

How do you find the number of…?

• Protons electrons neutrons

• Atomic atomic mass no.

Number number minus

(if neutral) At. No.

YOU NEED TO KNOW

• The Names (spelled correctly) and the Symbols (written correctly)

• “Naturally Occurring Elements in the Human Body”

Radioisotopes

• All elements with atomic numbers greater than 83 are radioisotopes meaning that these elements have unstable nuclei and are radioactive and some under 83 have isotope forms.

Isotope: form of an element with a different number of neutrons

What makes atoms radioactive?Their nuclei are unstable and

they break down at a constant rate over time…and they have uneven numbers of protons and neutrons. Radioactive Decay of Uranium

Some Radioactive Elements

Radioactive Particles Given Off

• Radioactive Decay of Uranium

Isotopes

• Are atoms of the same element that differ in the number of neutrons!

Number of neutrons? Isotopes? Which is the neutral form?

Which has more uneven number of protons and neutrons?

Number of Protons

Positive Uses of Radioisotopes

PET SCAN

Iodine-131 treat thyroid cancer

Sr 89 treat bone and prostate cancer

Uses of Radioisotopes

• Positron Emission Tomography

Sterillizing food and medical equipment

Radioactive dating

tracers

Cancer treatment

Technetium-99m

has become the most widely used (80%) radioisotope for diagnosing diseased organs (especially brain, heart, and bone)

Which are isotopes?

• 16 20 38 128 12 O F K I C

8 9 19 53 6 WHY?

20 38 128 F K I 9 19 53 different # neutrons

Formula

• Abbreviation for a compound

• A COMPOUND is two or more elements chemically bound:

Which are formulas?Abbreviation for a compound

• H2SO4 Cl2 H20 Al Why?

H2SO4 H20 abbreviations for compounds (2 or more different kinds of elements)

What is a compound?

• 2 or more different elements chemically joined (2+ diff.

capital letters)

• HCl H2O

• H2SO4 NOT O2

Which are atoms?

• C N N2 H20 Why?

• C and N only one in number

Using The Correct Term(get handout)

• Element• Compound

• Symbol• Formula

• Atom• Molecule

• 1 kind of Atom, Na, H• 2 or more different kinds of

elements chemically joined, NaCl• Abbreviation of an element, H, Cl

• Abbreviation of a compound Na2S

• 1 unit of matter H Na Cl• 2 or more atoms chemically

joined H2, NaCl

Which are compounds?

• Na N H2 NO2 H2O Why?

• NO2

• H2O

• 2 or more different elements chemically joined (2+ diff. capital letters)

What’s the difference?

• Co CO co

• Symbol formula nuttin

Which are molecules?

• Co CO CO2 O2 Why?

• CO CO2 O2 two or more atoms (alike or not alike, it doesn’t matter) bonded together

What are the four…• Most abundant elements in living

matter?

C H O N

What is the relative size?

• Proton neutron electron

• 1 amu 1 amu ~1/2000

• amu

• AMU=atomic mass unit= 1/12 CARBON ATOM

How do electrons arrange?

• In the outer shells?

• 2, 8, 8• Fill inner shell first, then

go to next shell out

Get kinda complicated beyond 2,8,8…so that’s all

we’ll do for now!

Atoms that have the same number of electrons have the same

chemical properties.

How many electrons in each shell?

• C O F Na

• 2,4 2,6 2,7 2,8,1

What are ions?

• Charged atoms

• Have lost or gained

an electron

Lost or Gained How Many e-?

• H+ Li+ Na+ K+

• Be+2 Mg+2 Ca+2

• Al+3

• F- Cl- Br- I-

• S-2

• Lost one e-

• Lost 2 e-

• Lost 3 e-

• Gained one e-

• Gained 2 e-

Note Ions and Formulas

• Na+ Cl-+1 -1 NaCl 1:1

• Mg2+ Cl-+2 -1 MgCl2 1:2

• Na+ S 2-+1 -2 Na2S 2:1

• Mg2+ S 2-+2 -2 MgS 1:1

Which are ions?

• Cl O-2 Na+1 N2

Why?

• O-2 Na+1

• Charged atoms (lost or gained electrons)

• show charges as superscripts

Which electrons determine…

• The chemical properties of the atom?

• Outermost shell

Periodic Table Hint:

• You can tell how many electrons are in an atom’s outermost shell by just looking at its position on the periodic table!!!!!

1 2

3 4 5 6 7 8

e- in outer shells

Which atoms combine…

• with other atoms?

• Ones that do not have filled outer electron shells

What is the driving force to make atoms join with other atoms to form compounds?

• TO HAVE FILLED OUTER ELECTRON SHELLS!!!!!!!!!!!!!!!!!!!!!!!!

How does an atom…

• Get a filled outer electron shell?

• Gaining, losing, or sharing electrons

If one electron is…

• Lost what charge will the ion have?

•+1

If one electron is gained…

• What charge will the ion have?

•-1

If 2 electrons are lost…

• What charge will the ion have?

•+2

If two electrons are gained…

• What charge will the ion have?

•-2

Making Correct Formulas:

• Note how the ion charge becomes the subscript of the other ion

• Na+ Cl- NaCl

• Mg2+ Cl- MgCl2

• Na+ S-2 Na2S

• Mg2+ S-2 MgS

What do we call the forces that…

• Hold atoms together in a molecule?

• Chemical bonds…not to be confused with James Bond

IONIC BOND

• What makes up ionic bonds?

• IONS

• WHY?

• Opposite charged ions attract

Covalent Bond

• What makes up covalent bonds?

• Atoms that are sharing electrons

Comparing Bonds

IONIC BOND (gain or lose e-)

COVALENT BOND (sharing e-)

How can covalent bonds be written?

• Single bond double bond triple bond

• C-C C=C C=C• C:C C::C C:::C