Student notes packet – Unit 6 1

Unit 6 – Atomic Structure & PeriodicityChapter 6 (Brown & LeMay, 9 th ed.)

Electronic Structure –

The electronic structure refers not only to the number of electrons that an atom has, but also to their _________________________ around the nucleus and to their _____________________.

Electromagnetic (EM) Radiation –

Speed of light = __________________________________ All types of EM radiation move through a vacuum at the speed of light. What does the term “vacuum” mean?

Copy all parts of Figure 6.3 (p. 200) in the space below:

Wavelength (λ) is the _______________________ between neighboring peaks (or troughs)o Units are meters (m) or nanometers (nm).o 1 nm = 1 x 10-9 m

Frequency (ν) is the number of ________________ that pass a given point each secondo Units are Hertz (Hz) or “per seconds” (s-1 or 1/s).o 1 Hz = 1 s-1

Frequency (ν) and wavelength (λ) are related to the speed of light:

Examples:1. The yellow light given off by a sodium vapor lamp used for public lighting has a wavelength of 589 nm.

What is the frequency of this radiation? (See Sample Exercise 6.2 on p. 202)

2. What is the frequency of radiation that has a wavelength of 640.0 nm?

3. An FM radio station broadcasts EM radiation at a frequency of 103.4 MHz (megahertz; 1 MHz = 1 x 106 s-1). Calculate the wavelength of this radiation.

c = λ ν

Student notes packet – Unit 6 2

TYPES OF ELECTROMAGNETIC RADIATION

Visible light corresponds to wavelengths between ____________ and ____________.

As wavelength increases, frequency ________________________. They are INVERSELY proportional.

LINE SPECTRA AND THE BOHR MODEL

Spectrum –

o Continuous spectrum –

o Line spectrum –

Bohr’s Model – Bohr used the line spectra of elements to create his model of the atom

o Bohr based his model on 3 postulates:1. Only orbits of certain radii, corresponding to certain

_______________________________, are permitted for electrons in an atom.2. An electron in a permitted _______________ has a specific energy and is in an

“______________” energy state. 3. Energy is only ______________________ or ____________________ by an electron as it

changes from one allowed energy state to another. This energy is emitted or absorbed as a photon with energy, E = ______ (where h = 6.63 x 10-34 J·s)

Examples:

1. Calculate the energy of one photon of yellow light whose wavelength is 589 nm. (Sample Exercise 6.3)

2. A laser emits light with a frequency of 4.69 x 1014 s-1. What is the energy of one photon of the radiation from this laser?

3. If the laser in #2 emits a burst of pulse of energy containing 5.0 x 1017 photons, what is the total energy of that pulse?

Student notes packet – Unit 6 3

Ground state (n = ____):

Excited state (n = ____________________):

STOP

CALCULATING ENERGY OF A PHOTON

Electrons jump from one level to another, absorbing or releasing energy:

Principal energy level

The energy related to the jump of an electron between energy levels can be calculated using the equation:

Examples: (i) Determine the amount of energy absorbed or emitted for each of the following transitions. Note whether

the energy was emitted or absorbed.

a. n = 3 to n = 1

b. n = 2 to n = 4

c. n = 1 to n = 2

∆ E=(−2.18 ×10−18 J) ( 1nf

2−1ni

2 )

Student notes packet – Unit 6 4

ELECTRON CONFIGURATION

Account for every electron in the atom Use the periodic table as a tool to count up the configuration Always start with the ______ orbital If bypassing a set of orbitals, write the maximum superscript number (i.e. s2, p6, d10, f14)

Full sequence: _____________________________________________________________________________

Noble Gas Notation – short cut! Use the symbol of a noble gas (group 18) in brackets to represent the configuration up to that element. Add on the remaining symbols necessary for your element.

Examples:

Element Ending Configuration Noble Gas Notation Full electron configuration

Sodium

Nickel

Germanium

Krypton

Sulfur

Student notes packet – Unit 6 5

ATOMIC ORBITALS

Holds a maximum of _____ electrons 4 types of orbitals:

HYBRID ORBITALS – Bonding

When an atom participates in a ____________________

bond, the 1 __-orbital and the 3 ___-orbitals combine and

reform into 4 new “sp3” hybrid orbitals.

Student notes packet – Unit 6 6

ORBITAL DIAGRAMS

Electron configuration – the way electrons are ______________________ among the various orbitals of an atom

Within an energy level (or principal quantum number), the relative energies of are:

You can also write the orbitals as boxes in a line, with increasing energy as you go right:

Fill out the electrons in the outermost energy levels for each of the following atoms. Consider the rules:(i) Max of 2 electrons per orbital(ii) You must fill an orbital type before moving on to the next (i.e. fill 1s before moving to 2s)(iii) Put 1 electron in each orbital of a type before pairing them up

1s 2s 2p 3s 3p 4s 3d 4p O:

1s 2s 2p 3s 3p 4s 3d 4p Ca:

1s 2s 2p 3s 3p 4s 3d 4p Mn:

1s 2s 2p 3s 3p 4s 3d 4p Ge:

Student notes packet – Unit 6 7

OXIDATION NUMBERS (a.k.a. OXIDATION STATE)

Represents the charge of an individual atom. Can be positive, negative, or zero. Refers to the number of electrons GAINED by an atom in a chemical bond. Ionic compounds contain ions where oxidation # = ______________________. Covalent compounds contain atoms that share electrons, and the number of electrons shared correlates

to the _____________________________________.

Use electron configuration to determine how many valence electrons Valence electrons are the electrons in the highest principal energy level (a.k.a. the BIG number) Combine s- and p-orbital electrons in outer energy level

Element Configuration# Valence electrons

Predict oxidation state

Lithium 1s2 2s1

Silicon 1s2 2s2 2p6 3s2 3p2

Bromine 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5

Germanium 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2

Beryllium 1s2 2s2

Where we get oxidation states of Transition Metals https://www.youtube.com/watch?v=E3Ok1qaXK_g

Electrons prefer to be STABLE (or lowest possible energy).

Empty orbitals are considered stable.

Full d-orbitals (2 electrons per box) is the most stable.

Half-full d orbitals stable also.

Electrons will move from 4s to 3d if it helps complete a full or half-full d level.

Examples:

3d4s[Ar]

3d4s[Ar]

3d4s[Ar]

Student notes packet – Unit 6 8

Fe Cu

Fe 2+ Cu (1 electron moves to 3d)

Cu +

Explaining oxidation states of elements:

3d4s[Ar]

3d4s[Ar]

3d4s[Ar]

3d4s[Ar]

3d4s[Ar]

Bromine’s oxidation states:

Silicon & Germanium’s +4 oxidation state:

Chromium’s +6 oxidation state:

Student notes packet – Unit 6 9

Pg. 9 (Students create for HW)

Watch videos:A. (5 min) https://www.youtube.com/watch?v=ov2ZHoXIBF0B. (5 min) https://www.youtube.com/watch?v=FvSinxeYWsA

Take notes on:

1. What are valence electrons?2. How to draw Lewis dot symbols3. Include the examples for F, Na, N, Al, and Cl

Student notes packet – Unit 6 10

Pg. 10 (Students create for HW)

1. Watch video (21 minutes)https://www.youtube.com/watch?v=NYFE5uslaNo

2. Take notes on the Steps for Lewis Dot Structures using the example H2O3. Also record the following examples: NBr3, O2, N2, CO2, and CO

Student notes packet – Unit 6 11

RESONANCE STRUCTURES(Use section 8.6 in your textbook to take notes on resonance structures.)Include:

Definition of resonance structures The Lewis structures of ozone (O3) What does a double headed arror indicated? The analogy of mixing paint (Fig. 8.11 in your book at home; Fig. 8.13 in your book in class) The resonance structures of the nitrate ion Sample exercise 8.10

Student notes packet – Unit 6 12

Resonance in benzeneo What is an “aromatic” molecule?o What is the molecular formula for benzene?o Draw the resonance structures for benzene (with C’s and H’s)o Draw the resonance skeletal structures for benzene (hexagons)o What are the bond lengths for a C-C and a C=C bond? How does this compare to the bonds

between carbons in benzene? How does this prove resonance structures?

Student notes packet – Unit 6 13

PERIODIC TABLE

Groups – columns (a.k.a. “Families”)o Numbered 1 – 18 OR IA – VIIIA/IIIB – IIB

Periods – rowso Numbered 1 - 7

Representative Elements

Transition Elements

1 – 18 notation 1, 2, 13 – 18 1 – 2, 13 – 18

A/B notation IA – VIIA(1A – 8A)

3 – 12

Student notes packet – Unit 6 14

PROPERTIES OF COMMON GROUPS

Alkali Metals (Group _____) Alkaline Earth Metals (Group _____)

Chalcogen family (Group _____) Halogens (Group _____)

Noble Gases (Group _____) Transition Metals

Student notes packet – Unit 6 15

PERIODIC TRENDS

Explaining the trendsThis is an important section—there is almost always an essay involving this topic on the AP exam. There are several arguments you will evoke to EXPLAIN a periodic trend. Remember opposites attract and likes repel. The trick is learning which argument to use when explaining a certain trend!

The Arguments

1) Effective nuclear charge, Zeff—essentially equal to the __________________. Think of the 1A group elements having a Zeff of

one while the 7A’s have a Zeff of 7! The higher the Zeff, the more positive the

nucleus, the more attractive force there is coming from the nucleus, drawing electrons in or holding them in place.

Relate this to ENERGY whenever possible.

2) Distance—attractive forces ________________________ with increased distance. Distant electrons are held loosely and thus easily

removed. Relate this to ENERGY whenever possible.

3) Shielding—electrons in the “core” effectively shield the nucleus’ attractive force for the valence electrons. Use this ONLY when comparing ___________________

the table, NOT across. There is ineffective shielding within a sublevel or energy level.

Relate this to ENERGY whenever possible.

4) Minimize electron/electron repulsions—this puts the atom at a ____________ energy state and makes it more ______________. Relate this to ENERGY whenever possible.

Student notes packet – Unit 6 16

ATOMIC RADIUS TREND

Atomic Radius – HALF the distance between two nuclei of the same element The edge of an atom is fuzzy and undefined, and we cannot measure it We can see the nucleus, so we use that to measure the distance between 2 nuclei and

divide by 2

ATOMIC radii decreases (___) moving across a period AND increases (___) moving down a row (family)

Use the arguments from page 15 to explain the trends:

Decreases left-to-right across a period:

Increases top-to-bottom down a group:

2r

Student notes packet – Unit 6 17

IONIC RADIUS TREND

Ionic radius – radius of the common ion form of the element

Use the

arguments to from page 15 to explain why:

Cations are ________________ than the neutral atom:

Anions are ________________ than the neutral atom:

Isoelectronic – ions contain the same number of ___________________

Isoelectronic series – group of ions and/or atoms with the same number of electrons

List the ions in the table in INCREASING order of ionic radius (smallest to largest):

o What element are the ions (in the table above) isoelectronic to? _______

o Give another example of an isoelectronic series:

Ion # of electrons Ion # of electronsN3- Na+

O2- Mg2+

F- Al3+

Student notes packet – Unit 6 18

IONIZATION ENERGY TREND

Ionization Energy – energy required to __________________ an outer electron from an atom IN THE GAS PHASE (COSTS energy)

Ionization Energy increases (___) moving across a period AND decreases (___) moving down a row (family)

Use the arguments to from page 15 to explain why:

↑ Across a period:

↓ Down a family:

Student notes packet – Unit 6 19

Subsequent Ionization Energies Removing each additional electron requires more energy:

o 1st IE – removal of 1st electron (from a neutral atom)o 2nd IE – removal of 2nd electron (from a +1 ion) > 1st IEo 3rd IE – removal of 3rd electron (from a +2 ion) > 2nd IE

A HUGE energy price is paid if the subsequent removal of electrons is from another sublevel or, another principal Energy level (core electrons)

o A large jump indicates a HUGE energy requirement to remove the electron.

o For Beryllium, this happens when the 3rd electron is removed b/c ___________________________________________________________________________________________________________

Determine the elements that have the following ionization energies:

Student notes packet – Unit 6 20

ELECTRONEGATIVITY TREND

Electronegativity (EN) – the ability of an atom IN A MOLECULE [meaning it’s participating in a BOND] to attract shared electrons to itself

_________________ is the most EN and __________________ is the least EN

Use the arguments to from page 15 to explain why:

F is the most electronegative element:

Fr is the least electronegative element:

***We’ll use this concept a lot in our discussions about bonding since this atomic trend is only used when atoms bond to form molecules.

Student notes packet – Unit 6 21

Bond Types Determined by ΔEN Subtract the EN values for the elements involved in the bond In reality, bond type is a spectrum. There is a little of each bond type character in each bond:

Examples of Bonds: ΔEN vs. Percent Ionic Character

What is the ΔEN of a bond that is 50% ionic, 50% covalent?

What range of ΔEN values would be considered an IONIC bond?

Covalent bonds are categorized into TWO types:

POLAR NONPOLAR

H H