Chemistry Unit 4 Test

What is effective nuclear charge?

The force of attraction the electrons on energy levels feel from the nucleus.

What is the effective nuclear charge that the valence electrons on Potassium (K) would feel?

+19 - 18e- = +1
Potassium's outer energy level would feel a +1 ENC

How do you find what electrons feel?

subtracting the number of valence electrons from the total number of electrons in the atom.

As you move left to right across a period... effective nuclear charge ___________,

Increases

As you move left to right across a period...atom size ___________

decreases

As you move left to right across a period...ionization energy ____________

increases

As you move left to right across a period...electronegativity ______________

increases

As you move down a group... effective nuclear charge

STAYS THE SAME,

As you move down a group... atom size

INCREASES,

As you move down a group... ionization energy

DECREASES

As you move down a group... electronegativity

DECREASES

Ionization energy is the energy required to

REMOVE AN ELECTRON FROM THE OUTER ENERGY LEVEL.

Electrons that are strongly attracted to the nucleus require

MORE energy to remove.

What is electronegativity? Why does it increase from left to right on the periodic table?

An atom's ability to attract/pull electrons closer to itself.
ENC increases from left to right on the P.T., so the nucleus's force of attraction on electrons is stronger as you go
towards the right, increasing its ability to pull in electrons.

Why does oxygen have a higher ionization energy than boron?

Oxygen has a stronger ENC, so it takes MORE ENERGY to remove an electron from it than Boron.

Why does gallium have a lower ionization energy than boron?

The valence electrons are further away from the nucleus in Gallium, so it's easier to remove one of those electrons,
thus needs LESS ENERGY to remove.

How do you find the number of neutrons?

mass number - atomic number

How do you find the atomic mass?

protons + neutrons

How do you find the valence electrons?

look at the group number

Why does electronegativity decrease as you go down the periodic table?

MORE ENERGY LEVELS creates more shielding from inner electrons and outer energy levels are further away from the
nucleus, making it more difficult (less ability) for the atom to pull electrons towards itself.

Why do atoms get larger as you go down the periodic table? Why do they get smaller as you go from left to right?

-Going down the P.T. = Adding MORE ENERGY LEVELS (rings) makes the atom size larger.
Going left to right = INCREASING ENC, so nucleus pulls in electrons closer, making the atom smaller

Why are cations smaller than neutral atoms? Why are anions larger than neutral atoms?

-Cations = more protons than electrons, so ENC is stronger, pulling in electrons more
-Anions = more negatively charged electrons cause more repulsion around electrons, causing them to spread out

How do you determine if a element is metal or non metal?