ATOMIC THEORY

IN THE BEGINNING

Atoms originally named by _____________

Believed the a substance could be divided over and over again only to a point

If divided further it would not be that substance anymore

His atoms were solid, homogeneous spheres

LAW OF CONSERVATION OF MASS

LAW OF DEFINITE PROPORTIONS

LAW OF MULTIPLE PROPORTIONS

JOHN DALTON

Proposed atomic theory in 1803 Parts of Theory

His atom is also a solid, homogeneous sphere

CATHODE RAYS

J.J. THOMSON’S MODEL

RUTHERFORD’S GOLD FOIL EXPERIMENT

RUTHERFORD’S MODEL

NIELS BOHR’S MODEL

COMPARING THE PARTICLES

In the nucleus Protons

Charge= ________ Mass = ___________________

Neutrons Charge= ______ Mass= ______________________

Surrounding the nucleus Electron

Charge= ______ Mass= _______________________

ELEMENTS

Composed of only one type of _________ Identity is based on ___________ number Atomic number (___)- number of protons

found in that atom (ID number for elements) Elements are ordered in periodic table according

to this number Mass Number (___)- mass of atom in atomic

unit Really the mass of the __________________________ Electrons are so tiny that they don’t count

CALCULATING PNE (GROUND STATE)

# of protons= __________________

# of electrons= _________________

# of neutrons= _______________________________

ISOTOPES

Different forms of the same atom type Differ by number of ____________ (so therefore

differ by mass as well) Isotope names- element name – mass

number Lithium-6 Lithium-7 Lithium-8

Atoms that lose or gain ___________ form ions Ions have a charge

Cation- ion with a ____________ charge Anion- ion with a _____________ charge

IONS

Forms when atoms _________ electrons

CATION

Forms when atoms __________ electrons

ANION

Cations With one common charge

“Name of the element” ion For example, Ca+2 is calcium ion

Multivalent “Name of element” (charge in Roman numerals) ion For example, Fe+2 is iron (II) ion

Anions “Name of the element with ending changed to –

ide” ion

For example Cl

- is chloride ion

NAMING IONS

CALCULATING PNE (IONS)

# of protons= atomic number

# of electrons = atomic number – charge for cations Atomic number + charge for anions

# of neutrons= mass number – atomic number

ATOMIC MASSES ON THE PERIODIC TABLE

Atomic masses on periodic table are an average of all naturally occurring ___________ based on their abundance

Calculating Atomic Mass

Need Mass of each isotope Fractional abundance of each isotope (must

change to fraction if given as %) For each isotope

Multiple the mass and the fractional abundance Add all of the answers together to get the atomic

mass

Proposed period table (1869)

Arranged elements according to ________________

Grouped elements by similar properties

Left holes for undiscovered elements and predicted their properties

Elements are arranged by _____________________

Elements occur in rows (or _________)- 7 periods in all

Elements occur in columns (or ___________________) with similar chemical properties- 18 in all

______________ law- elements can be organized into patterns in the table based on chemical and physical properties

The two series actually belong in the table like this, but we put them at the bottom to save space

Metal Good conductor of

electricity Malleable Ductile Shiny

Nonmetal Poor conductor of heat

and electricity Often gas or dull, brittle

solid Metalloid

Properties in between the other two

Most occur as solids

Br and Hg can occur as a liquid

Other occur as gas

Many elements can exist in different forms naturally

Carbon Both graphite and diamond are carbon, the

atoms are just arranged differently

Element occurs naturally in pairs 7 elements

Hydrogen (H2) Nitrogen (N2) Oxygen (O2) Fluorine (F2) Chlorine (Cl2) Bromine (Br2) Iodine (I2)