Chapter 7: Completing the Model of the Atom
Class Activity (there is no BW)
1. Send 1 student from your team to pick up enough white boards and markers for each person. 1 paper towel per team
2. Draw a Bohr model for the element I assign to you.
Class Activity (there is no BW)
2. Now, find all other students with the same number of occupied energy levels.
• Starting with Hydrogen’s group, stand together. Next, lithium’s group, finally sodium’s group.
• What do you notice?
Class Activity (there is no BW)
3. Now, find all other students with the same number of valence.
• Starting with Hydrogen’s group, stand together. Then, Beryllium’s group, etc.
• Then, boron’s group, etc. What do students notice?
What the Periodic Table Tells Us1. Columns are called “Groups” or “Families”– Main Group Elements are the tall ones!
• Groups 1 & 2, 13-18• They “follow the rules” pretty well. Behavior is predictable.• They tell us how many ______ the atoms of these elements have.• Groups #1&2 – Group # tells you how many • Groups 13-18- subtract 10 from the Group #
– Transition Elements are in between Main Group Elements• Groups 3-12• Behavior is less predictable!
– Inner Transition Elements are at the bottom of the P. Table
What the Periodic Table Tells Us
2. Rows are called “Periods”– They tell us the location of the _______ in atoms
of these elements.
Use the P. Table to Make an e- Diagram for an Element
• Ex: Lithium• Identify its Group #: 1
• Identify its Period #: 2
Q: So how many valence e-s does a lithium atom have? And where are they located?
A: 1 valence e- in the 2nd energy level
Light: Electromagnetic Spectrum• Energy can travel in waves. • There are high energy and low energy waves.• The ones we can see are called “the visible
spectrum.” ROY G BIV• Red is the low energy end: violet is the high
energy end.
Movement of e-’s
• e-s can jump to higher energy levels if they absorb energy.
• They can’t keep the energy so they lose it and “fall back” to lower levels.
• When they do this, they release the energy they absorbed in the form of light.
Movement of e-s, cont.
• When e-s absorb energy, they do so in certain amounts. (They “jump” specific distances.)
• When they release energy, they do so in certain amounts. (They “fall” specific distances.) And they release light that has that amount of energy.
• Question: if e-s fall a long distance, they release a lot of energy. What is the color that is likely to be released? (red end or purple end of spectrum?)
Emission Spectrum
• Def: Each element has a characteristic set of colors that are given off when its e-s “fall back.”
• You can identify an element by its emission spectrum!
• Emission spectrum of hydrogen
Emission Spectrum (cont.)
• See Fig 7.4 on p 235• H has 4 spectral lines (4 colored lines)• Mercury (Hg) has 11 lines! • Ne has 20+ lines!
Problem: there are more lines than you would expect if there are only a few energy levels.
Hypothesis: There must be many sublevels in an energy level
Electron Sublevels
Each electron has an “address,” where it can be considered to be located in the atom.
• Main energy level= “hotel”• Sublevel = “floor”• Orbital = “room” – Regions of space outside the nucleus– All orbitals in a sublevel have the same energy– 2 electrons max can fit in an orbital
Sublevels in Atoms
• See Fig 7.5 on p 235
Main energy level
Types of sublevels
# of orbitals # of electrons
1 s 1
2 s p
13 (4 total)
3 s p d
1 3 5 (9 total)
4-7 s p d f
1 3 5 7 (16 total)
Orbitals• s orbitals are spherical– There is only 1 orbital
• p orbitals are dumbbell shaped– There are 3 orbitals, all with = energy– Each is oriented on either x, y, or z axis– They overlap
• d orbitals have varying shapes– There are 5 orbitals, all with = energy
• f orbitals have varying shapes– There are 7 orbitals, all with = energy
Electron Configurations
• Electrons are always arranged in the most stable (lowest energy) way
• This is called“electron configuration”
Section 2: The Periodic Table & Atomic Structure
• Shape of p. table is based on the order in which sublevels are filled
REGIONS OF THE P. TABLE (see p 244 of book)• s REGION (“block”) - Groups 1 & 2• p REGION (block) - Groups 13-18• d REGION (block)- Groups 3-12 (Transition
Elements)• f REGION (block)- (Inner Transition Elements)
List sublevels from lowest to highest energy level (Using
P.Table)1. Always start with Period 1-go from L to R.2. Go to Period 2-from L to R3. Go to Period 3- from L to R4. Continue 4-7 periods, L to R until you have
completed the P. Table.• Exception: elements in d block are 1 main E.L lower
than the period where they are located• Exception: elements in f block are 2 main E.L.s
lower than the period in which they are located
Correct Order of Sublevels (lowest to highest energy)
• 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
Why Exceptions w/d & f block elements?
• When you get to the higher main E.L.’s, the sublevels begin to overlap.
E- configurations
• Use the P. Table to write the sublevels in increasing order, as previously instructed.
• Add a superscript next to each sublevel that shows how many e-s are in the sublevel
• Ex: Oxygen: 1s22s22p4
Valence e-s
• Valence e-s are the electrons in the highest occupied main energy level.
• Identify the valence e-s by finding the “biggest big number” in your e- configuration.Ex: Oxygen: 1s22s22p4
Question: WHAT IS THE BIGGEST BIG NUMBER YOU SEE? WHAT ARE THE VALENCE ELECTRONS?
Noble Gas Notation
• Short-cut way of showing e- configuration• A Noble Gas is a Group 18 element.1. Identify the noble gas in the period above your
element of interest. Write this symbol in brackets.
2.Write the e- configuration for any additional e-s that your element of interest has, but the noble gas doesn’t have.
Ex: Nitrogen: 1s22s22p5 becomes [He] 2s22p5
Practice Noble Gas Notation
• Tungsten (W)• E- configuration
• Noble Gas configuration
Arrow Orbital Diagram-Used to show e- configuration.
SYMBOLS:• A box represents an orbital– Label each box with the sublevel :1s 2s 2p
2p 2p
• An arrow represents an electron– 2 arrows (e-s) in the same orbital face opposite
directions.– Example: oxygen, see above
↑ ↓ ↑ ↓ ↑ ↓ ↑ ↑
Arrow Orbital Diagram-Used to show e- configuration.
INSTRUCTIONS:• Fill electrons from lowest to highest sublevel.• Never place 2 e-s in the same orbital of a
sublevel until you have placed one in each of the orbitals
Arrow Orbital Diagram: Practice
Regions or “Blocks” of the P. Table
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