Atoms, Elements, and the Periodic Table

PART 1: ATOMS

1. What are atoms made of?

NUCLEUS – center of the atom

PROTON (+) (in nucleus)

NEUTRON (0) (in nucleus)

ELECTRON (-) – surrounds the nucleus in a cloud.

An Atom – DON’T DRAW THIS ONE

NUCLEUS

PROTON

NEUTRON

ELECTRONS

What does an atom look like? (DRAW THIS ONE)

How many protons and electrons are there in an atom?

• The number of PROTONS & ELECTRONS in an atom are ALWAYS EQUAL.

How are electrons described in an atom?

•ELECTRONS form a cloud because we don’t know exactly where they are at any given moment.

What takes up the most space in a atom?

• Most of the atom is taken up by the space between the nucleus and the electrons.

What subatomic particle is the heaviest?

• Lightest to heaviest:

• electron<proton = neutron

What is an element?

An ELEMENT = any substance that cannot be broken down into simpler substances. An element is made of only 1 kind of atom.

Every atom of an element has the same number of protons.

Who was the first person to organize the elements?

Dmitri Mendeleev was the first person to organize the elements. He made the first periodic table.

• He organized it in order of increasing atomic mass.

How are the elements arranged today?

• The elements in today’s Periodic Table are arranged by their atomic number.

What is an atomic number?

• ATOMIC NUMBER = the number of protons in an atom. This tells you what kind of element it is. (at the top of the box)

What is a mass number?

• MASS NUMBER = The sum of the protons and neutrons in an atom. (not on the periodic table)

What is an isotope?

• ISOTOPE = Atoms with the same number of protons and a different number of neutrons.

DIFFERENT ISOTOPES OF CARBON

What is a chemical symbol?

• CHEMICAL SYMBOL = a short way of telling what the chemical is. It’s usually 1 or 2 letters. EXAMPLES:

Barium = Ba

Tungsten = W

What is atomic mass?

• ATOMIC MASS = the average mass of an element. This includes all the isotopes of that element.

mass mass mass+ +

3

321

What is a period on the periodic table?

• A PERIOD = a horizontal row in the periodic table. There are 7 of them.

• Elements in a period change from left to right according to a pattern. There is a trend that the elements follow.

PERIOD – HORIZONTAL

What is a group on the periodic table?

• A GROUP = A vertical column on the periodic table. Also called a FAMILY. There are 18 of them.

• Elements in a group all have similar characteristics. Groups are often named for the top element in the column. EXAMPLE:

Carbon group

Nitrogen family

GROUP or FAMILY – VERTICAL

12

MgMagnesium

24.305

ATOMIC NUMBER

CHEMICAL SYMBOL

CHEMICAL NAME

ATOMIC MASS

# of Protons = # of Electrons = # of Neutrons = Atomic Number = Mass # = Element Name =

Group # Period #