ATOMS AND ATOMIC THEORY

PERIODIC TABLE AND ITS PROPERTIES

CHEMICAL BONDS

THE ATOM

-The smallest piece of matter that still retains

the property of the element.

THE ATOM AND ITS PARTS

P NE

E

NUCLEUS

NEUTRONS

(no charge)

PROTONS (+)ENERGY LEVEL

ELECTRON (-)

ELECTRON CLOUD E

QUARKS = particles that make up protons and neutrons

-Quarks are held together by nuclear forces

-6 Quarks = Proton

-3 Quarks = Neutron

-How do they know this?

-Look at picture on pg. 508

IDENTIFYING ATOMS

Carbon

C

6

12

ATOMIC NUMBER

-# of protons

-# of electrons

-Tells you what type of atom you have

ATOMIC MASS

-# of protons + # of neutrons

-AMU = atomic mass unit = unit of measurement# of Neutrons = mass # - atomic #

BOHR MODELS and ELECTRON DOT DIAGRAMS-Show how electrons are arranged in energy levels.

-Use: 2n2

-Use: Atomic #

P/N

e

e

Stable Atoms:

-Have 2 e if they only have 1 shell

-Have 8 e if they have more than 1 shellNa

Cl

Electron-dot diagrams use the elements symbol and dots to show the # of electrons in the outer level

EVOLUTION OF THE ATOMIC MODEL

Famous Dead Guy = Democritus

Time Period = 400 BC

Experiment = None/Philosopher in Greece – He reasoned that all substances were made up of ATOMS

Results = Atoms were solids that couldn’t be subdivided = “UNCUTTABLE” ATOM

EVOLUTION OF THE ATOMIC MODEL

Famous Dead Guy = John Dalton

Time Period = 1800s

Experiment = Wanted to explain how and why elements combine together in fixed ratios, so he developed a theory

Results = Theory states: Each element has its own atoms which can rearrange/recombine with other atoms in chemical reactions. Idea of the atom = SOLID SPHERE

EVOLUTION OF THE ATOMIC MODEL

Famous Dead Guy = John Thomson

Time Period = 1904

Experiment = Used cathode-ray tubes with beams of electrons inside. The electrons were attracted to positive charges within the tube.

Results = The atom was a ball of positive charges with small negative particles called electrons **DISCOVERED THE ELECTRON*** Model of the atom = PLUM PUDDING MODEL

EVOLUTION OF THE ATOMIC MODEL

Famous Dead Guy: Ernest Rutherford

Time Period: 1911

Experiment:Shot alpha particles (positive charges) through Gold Foil. Some passed straight thru, others bounced off at angles

Results: Said the atom had a small core of positive charge surrounded by electrons

EVOLUTION OF THE ATOMIC MODEL

Famous Dead Guy: Niels Bohr

Time Period: 1913

Experiment: Noticed that each element had its own line spectra (light).This meant atoms could give off energy.

Results: Electrons exist on energy levels. When they get excited, the jump up a level and emit light.

- Electron Cloud Model = Current = ELECTRON CLOUD = electrons don’t travel on orbitals.

Electrons are found in the electron cloud = area around nucleus where electrons are most likely

found.

EVOLUTION OF THE ATOMIC MODEL

Each level of an atom can only hold a specific amount of electrons:

2n2

1st level: n=1: 2(1)2 = 2 electrons

2nd level: n=2: 2(2)2 = 8 electrons

3rd level: n=3: 2(3)2 = 18 electrons

4th level: n=4: 2(4)2 = 32 electrons

THE PERIODIC TABLE-Periodic = “Repeated in a pattern”

-Ex: phases of the moon, days of the week, calendars

-Periodic Table = way to organize the elements using patterns

-Developed by: Dmitri Mendeleev in the late 1800s

-Arranged in order of INCREASING ATOMIC # and by CHANGES IN PHYSICAL AND CHEMICAL PROPERTIES

-ATOMIC # always INCREASES from LEFT to RIGHT

-As you go from the left to the right, one proton and one electron are added to each

element!

THE PERIODIC TABLE

GROUPS: vertical columns

-AKA: FAMILIES

-# 1-18

-Elements in each group have SIMILAR PROPERTIES

-Ex: Group II = shiny metals, good conductors

-Elements in the same group have THE SAME # OF ELECTRONS in their OUTTER ENERGY

LEVEL

-This determines the CHEMICAL PROPERTIES of the element

THE PERIODIC TABLEPERIODS: horizontal rows

-Increase by one proton and one electron as you go left-right

METALS: On the left side of the table up to the metalloids

METALLOIDS: “Semimetals” - have properties of metals and nonmetals.

-Form a downward staircase

NONMETALS: On the right side of the table

-Also includes Hydrogen (found on the left)

SYMBOLS: 1-2 letter abreviation of the element

GENERAL TRENDS IN THE PERIODIC TABLE

ADD TO YOUR PERIODIC TABLE!!

-Electronegativity: An atom’s desire to GRAB another atom’s electrons

-Periods: It INCREASES from LEFT TO RIGHT

-why??

-Groups: It DECREASES as you GO DOWN a group

-why??

GENERAL TRENDS IN THE PERIODIC TABLE

-Ionization Energy: Amount of ENERGY required to REMOVE the outermost ELECTRON

-RELATED TO ELECTRONEGATIVITY

-Periods: INCREASES from the LEFT to the RIGHT

-Why?

-Groups: DECREASES as you go DOWN a group

-Why?

GENERAL TRENDS IN THE PERIODIC TABLE

-Reactivity: How LIKELY/vigorously an atom is to REACT with other substances

-Determined by how easily electrons can be removed (ionization energy) and how badly an atom wants to take other atom’s electrons away (electronegativity)

-Metals:

-Periods: DECREASES from LEFT to RIGHT

-Groups: INCREASES as you go DOWN

-Nonmetals:

-Periods: INCREASES from LEFT to RIGHT

-Groups: DECREASES as you go DOWN

GENERAL TRENDS IN THE PERIODIC TABLE

-Melting Point:

-METALS: DECREASES as you go DOWN

-NONMEALS: INCREASES as you go DOWN

PROPERTIES OF METALS

-Malleable = they can be HAMMERED into THIN SHEETS

-Ductile = they can be DRAWN into WIRES

-Most are HARD, SHINY SOLIDS

-GOOD CONDUCTORS of electricity

-Ex: Copper, Gold, Silver

-Some are MAGNETIC

-Ex: Cobalt, Nickel, Iron

METAL FAMILIES1. ALKALI METALS (Group 1)

-1 valence electron (in their outer shell)

-Highly Reactive (want to give away their one electron to become full and stable)

-Shiny, Malleable, and Ductile

-Good Conductors

-Never found alone in nature

because they are the most reactive metal

METAL FAMILIES

2. ALKALINE EARTH METALS (Group 2)

-2 valence electrons

-Very Reactive (want to give away their 2 electrons to become full and stable)

-Shiny, Malleable, and Ductile

-Never found alone in nature)

METAL FAMILIES

3. Transition Metals (Groups 3B - 12B)

-1, 2, or 3 valence electrons

-Less Reactive than groups 1 and 2

-Some are MAGNETIC (Iron, Nickel, and Cobalt)

-Some are very good CONDUCTORS (Copper, Gold)

-MERCURY is the ONLY LIQUID METAL

METAL FAMILIES

4. Synthetic Elements (Manmade)

-Most are in Periods 6 and 7

-11 are in the ACTINOID and LANTHANOID series

-RADIOACTIVE

PROPERTIES OF NONMETALS

-GROUPS 7A AND 8A

-SOLIDS, LIQUIDS, or GASES at room temp.

-DULL in color

-VERY BRITTLE

-POOR CONDUCTORS

NONMETAL FAMILIES

1. Hydrogen

-1 electron, 1 proton, 0 neutrons

-HIGHLY REACTIVE (the Hindenburg??)

-Very LIGHT

-FLAMMABLE

-Makes up 90% of all atoms in the universe

2. Halogens (Group 7A or 17)

-7 valence electrons

-HIGHLY REACTIVE (want to steal 1 electron to be full/stable)

-Salt Formers (ex. NaCl)

-MOST REACTIVE NONMETALS

NONMETAL FAMILIES

NONMETAL FAMILIES

3. Noble Gases (Group 8A or 18)

-Complete outer shell

-Helium has 2 on the 1st shell = full

-The rest all have 8 = full

-DO NOT FORM COMPOUNDS (b/c they’re stable)

MIXED GROUPS:

METALS, NONMETALS, METALLOIDS

GROUPS 13-16 (3A-6A)

1. Boron Group (Group 3A or 13)

-3 valence electrons

-A few are SEMICONDUCTORS

2. Carbon Group (Group 4A or 14)

-4 valence electrons

-Carbon = nonmetal

-Silicon/Germanium = metalloids

-Tin/Lead = metals

MIXED GROUPS:

METALS, NONMETALS, METALLOIDS

GROUPS 13-16 (3A-6A)

MIXED GROUPS:

METALS, NONMETALS, METALLOIDS

GROUPS 13-16 (3A-6A)

3. Nitrogen Group (Group 5A or 15)

-5 valence electrons

-Nitrogen = 78% of our atmosphere

-N/P/As = nonmetals

-Sb = metalloid

-Bi = metal

MIXED GROUPS:

METALS, NONMETALS, METALLOIDS

GROUPS 13-16 (3A-6A)

4. Oxygen Group (Group 6A or 16)

-6 valence electrons

-Oxygen = 21% of our atmosphere

-O/S/Se = nonmetals

-Te/Po = metalloids

ISOTOPES

Isotope = Atoms of the same element that have different numbers of neutrons

ex: Carbon-12 = nonradioactive (6 P and 6 N)

Carbon-14 = radioactive (6 P and 8 N)

Atomic Mass v/s Average Atomic Mass

- Atomic mass = protons + neutrons in a single atom

- Average Atomic mass = average mass of the mixture of an element’s isotopes