Atomic number = # of protons = # of electrons (neutral atom)

Atomic number = # of protons = # of electrons (neutral atom)

Atomic mass

Carbon has an atomic number of 6, which means it has 6 ________ in its nucleus and 6 __________ orbiting around the nucleus.

protonselectrons

Organization of Your Periodic Table

He, Ne, and Ar are in the same ___________.

C, N, and O are in the same ___________.

P E R I O D SGROUPS

Page 168-169

Organization of Your Periodic Table

Atomic mass

*** Atomic # ***Similar properties:

Reactivities

Electron Configurations (groups)

Families

Get out your color coded periodic table!!!

Metals

Excellent conductors (Sea of electrons) even as solids

Mobile electrons

Metals are malleable and ductile

Can be pounded into sheet

Can be pulled into wire

Alkali Metals

Similar properties:

Group # 1

Reactive

Good Conductors

Alkaline Earth Metals

Similar properties:

Group # 2

Reactive – but less than alkali

Good Conductors

Metals

Excellent conductors (Sea of electrons) even as solids

Mobile electrons

Metals are malleable and ductile

Can be pounded into sheet

Can be pulled into wire

Noble Gases

Similar properties:

Group # 18

NON-reactive

Gases

Full outer shells!!!

Halogens

Similar properties:

Group # 17

Very reactive

Fluorine and Chlorine = gases

7 valence electrons

Transition metalsSimilar properties:

Generally least reactive metals

Tricky valence (can change from the expected)

Mostly form +1, +2, and +3 ions

Red = ?Green = ?

Blue = ?

Good Conductors = ?

Inert elements = ?

Review1. What element is in Group 2,

Period 3?

2. Name an element in Group 3

3. How many valence electrons in Xe?

4. Give me an element with 1 valence electron.

Periodic TrendsAtomic radius:- Measure of size – radius of an atom

- Atoms with more electrons do NOT necessarily have a larger atomic radius

Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius

Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius

1. Atoms get larger going down a group.

2. Atoms get smaller going across a period

So why?...

Periodic Trends- Atoms with more electrons do NOT necessarily have a larger atomic radius

As you move across a period, # of protons increases and outermost energy level stays the same, attractive force between elecs. and pros. pulls the atom tighter (closer to nucleus)

Periodic TrendsWhat’s bigger:

B or Al

B or N

N or Zn

C or Cl

Periodic TrendsIonization energy – energy needed to remove one electron from an atom

Li → Li+ + e-

… indication of how strongly an atom holds onto its outermost elecs.

Periodic TrendsThe graph on page 178 shows how ionization energies vary with atomic #

What element does the black point at (10, 2100) represent?

With respect to the periodic table ionization energies show 2 important trends…

Periodic TrendsWith respect to the periodic table ionization energies show 2 important trends…

1. Decrease as you move down a group

2. Increase as you move left to right across a period

Periodic Trends

How does the ionization energy trend compare to the atomic radius trend?

Does this make sense?

Periodic Trends

O

Be

Be

Cl

------

What’s bigger: ↑er I. E.:

O or C

Be or Ca

Na or Be

Cl of Al

Ca or B+3

IN NOTES

Periodic Trends

O

Mg

Be

Cl

------

What’s bigger: ↑er I. E.:

O or B

Mg or Sr

K or Be

Cl of Si

Sr or Al+3

IN NOTES

Periodic TrendsSuccessive Ionization energies (removing more than one electron from an atom):

- The 2nd > 1st, the 3rd > 2nd, the 4th > the 3rd

- but if you look at the I. E. s there is usually a large jump. Where? PAGE 178

Periodic TrendsHow does atomic radius change?

Why?

How does ionization energy change?

Why?

With respect to the periodic table ionization energies show 2 important trends…

1. Decrease as you move down a group

2. Increase as you move left to right across a period

How does the ionization energy trend compare to the atomic radius trend?

Does this make sense?

What’s bigger: ↑er I. E.:

O or K

Mg or Mg+2

S-2 of F-1

Octet Rule = ?

Octet rule – Atoms tend to gain, lose, or share electrons in order to acquire a full set of valence electrons (8) [2 for H, He, Li, Be, + B]

What is electronegativity?

How does it increase on the p. t. ?

In this bond: Mg—O, which way do

elecs. Shift? WHY?

Electronegativity – ability to attract electrons in a bond

O, > electroneg.

Bigger down a group and smaller across a period

How does atomic radius change?

Why?As you move down a group, there are additional energy levels

As you move across a period there are additional protons pulling the electron in tighter

Negative ions get bigger

Positive ions get smaller

How does ion size change?

Why?

Negative ions gain electrons

Positive ions lose electrons

Opposite of size (atomic radius)

How does ionization energy change?

Why?

Electrons are closer to the nucleus and held tighter in smaller atoms

Away from the middle

How does reactivity change?

Why?

Atoms on the outside of the p.t. are closer to achieving the octet rule and so more reactive

Up and to the right (Fr to F)

How does electronegativity change?

Why?

Elements on the right side of the periodic table want electrons to satisfy the octet rule