Prep for General Chemisty Ch. 3

Element

A pure substance that cannot be broken down into simpler substances

Atom

The smallest particle of an element

Elements are represented by

Chemical symbols

Chemical symbol rule

First letter capitalized, second letter lowercase if present

Symbol for sulfur

S

Symbol for silver

Ag

Symbol for helium

He

Symbol for tungsten

W

Symbol for carbon

C

Symbol for nitrogen

N

Symbol for fluorine

F

Symbol for oxygen

O

Symbol for cobalt

Co

Symbol for calcium

Ca

Symbol for aluminum

Al

Symbol for magnesium

Mg

Symbol for iron

Fe

Symbol for phosphorus

P

Correct symbol for calcium

Ca

Correct symbol for nitrogen

N

Correct symbol for iron

Fe

Element represented by S

Sulfur

Element represented by P

Phosphorus

Element represented by Ag

Silver

Periodic table

Organized arrangement of elements based on atomic number

Period

Horizontal row on the periodic table

Group (family)

Vertical column on the periodic table

Elements in the same group have

Similar chemical properties

Elements in the same group have

Same number of valence electrons

Group 1 name

Alkali metals

Group 2 name

Alkaline earth metals

Group 17 name

Halogens

Group 18 name

Noble gases

Noble gases are

Colorless and odorless

Group 17 Period 4 element

Bromine (Br)

Group 2 Period 3 element

Magnesium (Mg)

Group 15 Period 2 element

Nitrogen (N)

Metals location on periodic table

Left side of zigzag line

Nonmetals location on periodic table

Right side of zigzag line

Metalloids location on periodic table

Along zigzag line

Metal properties

Shiny, ductile, good conductors

Nonmetal properties

Poor conductors, dull, brittle

Metalloid properties

Intermediate between metals and nonmetals

Metalloids are used as

Semiconductors

Sodium classification

Metal

Chlorine classification

Nonmetal

Silicon classification

Metalloid

Iron classification

Metal

Carbon classification

Nonmetal

Democritus

Proposed matter is composed of atoms

Democritus lived around

400 BC

Democritus believed atoms were

Indivisible

Aristotle believed matter was

Continuously divisible

Scientist who rejected atomic theory initially

Aristotle

Dalton published atomic theory in

1808

Dalton’s atomic theory

Elements are made of indivisible atoms

Dalton’s atomic theory

Atoms of the same element are identical

Dalton’s atomic theory

Compounds form when atoms combine

Dalton’s atomic theory

Atoms are not changed in chemical reactions

Scientist who discovered the electron

J.J. Thomson

Year electron discovered

1897

Charge of electron

-1

Electron charge in coulombs

-1.60 × 10^-19 C

Electron mass

9.11 × 10^-28 g

Cathode rays were shown to be

Electrons

Scientist who discovered the proton

Thomson

Charge of proton

+1

Proton charge in coulombs

+1.60 × 10^-19 C

Proton mass

1.673 × 10^-24 g

Plum pudding model

Electrons embedded in positive sphere

Neutral atom

Equal numbers of protons and electrons

Charged atom

Unequal numbers of protons and electrons

Scientist who performed gold foil experiment

Rutherford

Year of Rutherford experiment

1910

Particles used in gold foil experiment

Alpha particles

Result of gold foil experiment

Most particles passed through foil

Unexpected gold foil result

Some particles bounced back

Rutherford’s conclusion

Atom contains dense positive nucleus

Diameter of atom

About 10^-10 m

Diameter of nucleus

About 10^-15 m

Most of atom’s mass is located in

Nucleus

Most of atom’s volume is occupied by

Electron cloud

Scientist who discovered neutron

Chadwick

Year neutron discovered

1932

Charge of neutron

0

Neutron mass

1.675 × 10^-24 g

Location of proton

Nucleus

Location of neutron

Nucleus

Location of electron

Outside nucleus

Subatomic particles

Protons, neutrons, electrons

Most massive subatomic particles

Protons and neutrons

Least massive subatomic particle

Electron

Protons determine

Identity of element

Atomic number

Number of protons

Atomic number symbol

Z

All atoms of same element have same

Atomic number

Atomic number of sodium

11

Atomic number of nitrogen

7

Atomic number of sulfur

16

Atomic number of barium

56