4.2 A guided tour of the Periodic Table

I CAN:

-RECOGNIZE THAT ATOMS CAN BECOME CATIONS AND ANIONS BECAUSE THEY GAIN OR LOSE ELECTRONS.

-RECOGNIZE THE ATOMIC NUMBER WILL STAY THE SAME AND DUE TO ISOTOPES THE MASS NUMBER CHANGES.

-CALCULATE THE ATOMIC NUMBER, MASS NUMBER, CHARGE, AND IDENTITY OF THE ELEMENT BASED ON THE PROTONS, NEUTRONS, AND ELECTRONS

What is the purpose of the periodic table?

To organize elements so you can find what you need to know quickly.

Organization of the periodic table.

Properties can be predicted based on where the element is located.

Based on # of protons. hydrogen=1, helium-2, etc.

Periodic Law: repeating chemical and physical properties of elements change periodically with the atomic number of elements. This meaning will become much clearer soon!

The periodic table helps determine electron arrangement

Horizontal rows=periods Based on number of protons.

Can also determine electrons.

Electron configurations.

Energy level, orbital, number of electrons.

Carbon 1s2

2s2

2p2

Elements in the same group have similar properties

Groups: vertical column of elements

Valance electrons determine chemical properties

Elements in same group have some number of valance electrons therefore…

Some Atoms for Ions

Why are Group 1 elements reactive?

Atoms that do not have filled outer layers undergo ionization. Gain or lose electron.

Will no longer have the same number of electrons as protons (charged) Ion: has lost or gained electron, has positive or negative charge.

Positive ions (lost electron)= cations

Lithium

Negative ions (gained electron)=anions

Fluorine

How do Structures of Atoms Differ?

Atomic number (Z): Number of protons

Mass Number (A): the sum of the number of protons and neutrons in the nucleus. Fluorine has 9 protons and 10 neutrons=?

Oxygen has 8 protons and 8 neutrons=?

Why aren’t electrons included in mass?

Atoms of each element will always have same atomic number, but may have different mass numbers.

Isotopes

An atom that has the same number of protons as other atoms of the same element do but that has different number of neutrons. 3 times the mass.

Calculating the number of neutrons in an atom

Uranium: Atomic number=92

Mass Number=235

Number of neutrons: 143

The mass of an atom

Fluorine atom has a mass less than one trillionth of a billionth of a gram.

Atomic mass unit (amu): a unit of mass that describes the mass of an atom or molecule; it is exactly one twelfth of the mass of a carbon atom with a mass number of 12.

Average atomic mass: the weighted average of the masses of all naturally occurring isotopes of an element.