Periodic Table

Periodic Table- An arrangement of elements in columns based on properties that repeat from row to row.– First organized by Dimitri Mendeleev,

modeled after the card game solitaire– Elements were arranged into rows by

increasing mass– Similar properties were placed in the same

column

Today’s periodic table is arranged by atomic number–The atomic number increases as you move left to right

–PERIOD - rows across–GROUP – columns up & down

Review - ELEMENTS

Can not be chemically broken down into simpler substances

Arranged into 3 groups on table:

metals, metalloids, non- metals

From left to right on the table elements become less like metals

METALS

good conductors of electricity and heat, usually solid at room temperature, malleable, reactive

Blue elements on YOUR table–TRANSITION METALS – special

group of metals found in the middle section of the table, (groups 3-12)

METALLOIDS

Properties are in between the properties of metals and non- metals

All elements that share a border on the “Staircase” on your table

Non- Metals

Poor conductors. Can be solid liquid or gas at room temperature, not reactive

Red elements on YOUR table

Matter &The Atom

Matter

The term matter describes all of the physical substances around us

Matter is anything that has mass and takes up space

The Universe is made up of matter and energy

*Matter is made up of atoms.*An atom is the smallest whole particle of matter. Atoms are the building blocks of matter.* Sub-Atomic particles are the tiny particles that make up an atom.

Atomic Structure

NUCLEUSThe center of the atom.

All the particles are inside or around the nucleus

Atomic Structure

proton (p+)

neutron (no)

electron (e-)

Atomic Structure

Proton (p+)

Located in the nucleus of the atom

Protons have a positive charge (+)

 Much larger and heavier than electrons

Number of protons is different for each element. If the number of protons changes, the element changes.

Atomic Structure

Neutron (n0)

Located in the nucleus of the atom

Neutral particle (has no electrical charge)

Largest particle, a bit bigger than a proton 

Atomic Structure

Electron (e-)

Found in a cloud outside the nucleus

Electrons have a negative charge (-)

Smallest particle

Orbit nucleus on energy levels

Atomic Number = number of protons in each atom of any element

All atoms want to balance their protons and electrons to be NEUTRAL (no electrical charge)

In a neutral atom, the # of protons = the # of electrons

Element Atomic # # protons

Hydrogen 1 1

Gold 79 79

Oxygen 8

Iron 26 26

Lead 82

Helium 2

Sodium 11 11

Sulfur 16

Atomic Mass– the sum of the mass of all the protons and neutrons in an atom

-- measured in Atomic Mass Units (amu)

Mass Number – sum of protons and neutrons in the nucleus

--can be used to find the number of neutrons in the nucleus Mass # = atomic # + n or n = mass # - p

ATOMIC NUMBER

the number of (p+) and (e-)

(+) = (-)

ATOMIC MASS

(MASS NUMBER)

PROTONS (+) + NEUTRONS (0)

PROTONS AND NEUTRONS = NUCLEUS

79

Au

19

7

Isotope – when an atom has a different number of neutrons than other atoms of the same element–Example: 2 Oxygen Atoms,

one has 8 neutrons one has 9.

IsotopesThe number of protons for a given atom never changes.

The number of neutrons can change. 

Two atoms with different numbers of neutrons are called isotopes

Isotopes have the same atomic #

Isotopes have different atomic Mass #’s

ElectronsElectrons can be found in the electron cloud.

Energy Levels – electrons are located on these levels based on their energy

•The lowest energy level is closest to the nucleus--It holds 2 e-•The 2nd energy level holds 8 e-

•The 3rd energy level holds 8 e-

•ELECTRONS FILL THE LEVELS FROM INSIDE OUT.

Electrons can change levels when energy is added to or removed from the atom–If an e- gains energy it is in

“excited state” and moves out an energy level

–If it loses energy it goes in an energy level

Valence Electrons - Number of electrons in outside row– Identified with a Roman numeral number at

the top of each group– All elements in each group have the same

number– Column VIII (group 18) has 2, 8 or 18 – it

is FILLED!– Transition metals have no specific roman

numeral

PT COMMANDMENTS

For atoms and elements

1.

All atoms want to fill their outer energy level.

2.

The roman numeral columns tell you how many electrons an atom has currently in its outside level.

3.

THE SUBATOMIC PARTICLES ARE:

ELECTRONS (-) NEGATIVE electrical

charge

PROTONS (+) POSITIVE electrical

charge

NEUTRONS (0) NO electrical

charge

4.

Protons have a mass of 1 atomic mass unit (AMU)

Electrons have almost zero mass (0 amu).

5.

79 ATOMIC NUMBER

Au (the number of (p+) and (e-) )

197 (+) = (-)

6. ATOMIC MASS

PROTONS (+) + NEUTRONS (0)

**don’t forget, protons and neutrons are in the nucleus!

2 electrons

8 electrons

18 electrons

Nucleus

p+ and n0

maximum number of

electrons ineach orbit