Atom

the smallest

particle of an

element

Nucleus

the dense, positively charged

mass located in the center of an atom

Proton

a positively charged

subatomic particle that is found in

the nucleus of an atom

Neutron

a neutral subatomic

particle that is found in

the nucleus of an atom

Electron

a negatively charged

subatomic particle that is found in the

space outside the nucleus of

an atom

Subatomic

A term that

means 'smaller than an atom'

Particle

a very small piece

of something

Thomson

• The man who discovered the electron.

• This disproved one important point of Dalton's atomic theory:

– Atoms cannot be subdivided, created, or destroyed.

• The Plum Pudding model of the atom by Sir Thomson clearly differentiated between the positive and negative regions of an atom

Dalton

• Created the atomic theory:

– All matter is composed of small particles called atoms

– All atoms of a given element are alike

– Compounds are formed when different atoms combine in fixed proportions

– A chemical reaction involves the rearrangement of atoms

Dalton’s Model

Rutherford

• The man who discovered the nucleus of an atom.

• The Rutherford model of the atom was simplified in a well known symbol showing electrons circling around the nucleus like planets orbiting the sun.

• The element 'rutherfordium' was named in Rutherford’s honor.

Gold Foil Experiment

The experiment

conducted by Ernest

Rutherford to discover the

nucleus of an atom.

Isotopes The term given to atoms of the same element

that have different

numbers of neutrons.

In atoms that are radioactive,

the time required for half of the element to

decay.

Half-life

Decay

To break into

smaller pieces.

Bohr

• The man who discovered electron energy levels.

• The Bohr model shows that the electrons in atoms are in orbits of differing energy around the nucleus (think of planets orbiting around the sun).

• Bohr used the term energy levels (or shells) to describe these orbits of differing energy.

Electron Cloud Model

• The current model for atomic structure.

• No way to know exactly where an electron is at any moment in time.

• We can only approximate, or guess, where an electron is located.

• According to something called quantum theory, an electron can be found anywhere around the nucleus.

A form of matter that cannot be

separated into simpler

substances by ordinary chemical methods.

Element

Energy Levels the possible energies that electrons in an atom can have

Energy Level (Principal Quantum Number)

Shell Letter

Electron Capacity

1 K 2

2 L 8

3 M 18

4 N 32

5 O 50

6 P 72

Mass Number

the sum of the number of protons

and neutrons in the

nucleus of an atom

Atomic Number

a unique number for

each element that equals the

number of protons in an atom of that

element

Periodic Table

an arrangement

of elements in columns based

on a set of properties that

repeat from row to row

Group

• When a column goes from top to bottom, it's

called a group.

• The elements in a group have the same

number of electrons in their outer orbital.

• Those outer electrons are also called valence electrons. They are the

ones involved in chemical bonds with

other elements.

Periods

• each of the rows is considered to be a different period.

• In the periodic table, elements have something in common if they are in the same row. All of the elements in a period have the same number of atomic orbitals.

• Every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.

• At this time, the maximum number of electron orbitals or electron shells for any element is seven.

Periodic Law

physical and chemical properties

of the elements recur in a systematic and predictable way

when the elements are

arranged in order of increasing atomic

number.

Metals

• elements that are good conductors of heat and electric current

• Almost 75% of all elements are classified as metals.

• What are the characteristics of metals? – Conduction

– Reactivity

– Chemical

– Alloys

Non Metals • Nonmetals share many similar properties including: – They are either gas or

solid under standard conditions.

– They are very brittle in their solid form.

– They are not malleable or ductile.

– They generally have lower densities than metals.

– Poor conductors of heat and electric currents

Noble Gases

• the elements in Group 8A of the periodic table

• They are located to the far right of the periodic table.

• Elements in the noble gas family have atoms with a full outer shell of electrons.

• They are also called the inert gases

Halogens • the elements in Group 7A of the periodic table

• have seven electrons in their outer shell. That seven-electron trait applies to all of the halogens.

• they have the trait of combining with many different elements.

• They are very reactive. You will often find them bonding with metals and elements from Group One of the periodic table.

Alkali Metals • the elements in Group 1A of the periodic table, not including hydrogen

• They are very reactive. • They all have one electron in

their outer shell. That's one electron away from being happy (full shells).

• An increased desire to bond means you are more reactive.

• some of these pure elements in water (H2O), can cause huge explosions.

• They are malleable (bendable) and sometimes soft enough to be cut with a dull knife.

Hydrogen not included

Alkali Earth Metals

• the elements in Group 2A of the periodic table

• This is the second most reactive

• they are likely to form solutions with a pH greater than 7

• Each of them has two electrons in their outer shell. They are ready to give up those two electrons in electrovalent/ionic bonds

Metalloids

• elements with properties that fall between those of metals and nonmetals

• found along the stair-step line that distinguishes metals from non-metals.

• Metalloids have properties of both metals and non-metals.

• Some are semi-conductors. This means that they can carry an electrical charge under special conditions

Octet Rule • atoms will readily bond

with other atoms to have 8 electrons in the outer shell

• Atoms tend to gain, lose or share one or more of their valence electrons to achieve a filled outer electron shell

Ion • a charged atom, with more

or less electrons than neutrons.

– Cations are ions with a net positive

charge. Examples : Silver: Ag+, hydronium: H3O

+, and ammonium: NH4

+

– Anions are ions with a net negative charge. Examples: hydroxide anion: OH-

, oxide anion: O2-, and sulfate anion: SO4

2-

Lost Electron Gained Electron

Valence Electrons

• An atom's number of electrons occupying the last outermost shell..

• In general, the number of valence electrons of a element is equal to the group number

Dmitri Mendeleev • Father of the Periodic Table

• arranging the 63 known elements into a Periodic Table based on atomic mass

• arranging the elements in ascending order of atomic weight and grouping them by similarity of properties.

• He predicted the existence and properties of new elements and pointed out accepted atomic weights