Atomic Structure & Periodic Table

Atoms

The smallest part of an element any smaller and it is no longer that element!

There is a different atom for each element.The number of protons determine the element.

3 protons = Lithium20 protons = Calcium

IF an atom has no charge, then the number of protons (positive charges) equals the number of electrons (negative charges).

Protons

Have a positive chargeEquals the atomic numberEquals the number of electrons, if the atom has

no chargeDetermines the type of elementLives in the nucleus with neutrons

Neutrons

Have no charge

Have mass. So you compute neutrons by atomic mass – atomic number (protons)

Live in the nucleus with the protons

Can vary without changing the type of element

Electrons

Have a negative charge

Can give you the identify of the element IF the atom has no charge

Has almost no mass

Can vary without changing the type of element

Atomic Number

Located above the element’s symbol

Always tells the number of protons and sometimes the number of electrons IF the atom is neutral (no charge)

Atomic mass

The number of protons plus neutrons in an atom. Almost all of the mass is located in the nucleus because electrons have such little mass.

Is often indicated by the name of the element followed by the mass. Example Lithium – 7

Can vary without changing the type of element

Periodic Table

Arranged by

Increasing atomic number (protons)

Why isn’t it arranged by increasing atomic mass?

Periods

Rows

Indicate the number of electron clouds each atom of that element has

NOT ALWAYS THE SAME STATE OF MATTER AT ROOM TEMPERATURE

Families or groupsColumns

All have the same number of electrons in their valence (same number of valence electrons)

All react similarly and have similar physical and chemical characteristics

NOT ALWAYS THE SAME STATE OF MATTER AT ROOM TEMPERATURE

Metals

left of the “zig zag”/staircase.

Metals are:shiny, ductile, malleable, thermally and electrically conductive

MOST but not all are solids

Nonmetals

Located to the right of the “zig zag” or staircase

MOST are gasses at room temperature.

Characteristics of nonmetals include: dull, brittle when they’re a solid and not good

conductors of thermal or electrical energy

Metalloids

Located on the zig zag line.

Have characteristics of BOTH metals and nonmetals in each

Reactivity

The elements on the left of the periodic table are more reactive then the ones to their right.

As you move from left to right, reactivity decreases

Hydrogen

Reacts like a metal but has the characteristics of nonmetals.

The most abundant element in the universe

Describe an atom

Using potassium, describe the atom using the following words:

Proton, neutron, electron, electron clouds, nucleus