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Benchmark Review—important notes. Electron Configuration. Rules for filling orbitals. There are three rules for filling orbitals . Aufbau Principle: Electrons always fill the lowest energy levels first . Electrons start at the bottom and work their way up .

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Rules for filling orbitals
Rules for filling orbitals

There are three rules for filling orbitals.

  • Aufbau Principle: Electrons always fill the lowest energy levels first.

    • Electrons start at the bottom and work their way up.

    • This also implies that electrons fill orbitalsthe same way every time.

  • Pauli Exclusion Principle: No two electrons with the same energy characteristics can occupy an orbital at the same time.

    • One electron must be spin up and the other electron must be spin down.

  • Hund’s Rule: When filling multipleorbitals of the same sublevel (p, d, and f), electrons half-fill the sublevel first before pairing electrons.



Order for filling orbitals
Order for Filling Orbitals

  • 7s 7p 7d 7f

  • 6s 6p 6d 6f

  • 5s 5p 5d 5f

  • 4s 4p 4d 4f

  • 3s 3p 3d

  • 2s 2p

  • 1s


Connections to the periodic table
Connections to the Periodic Table

  • The first two columns of the periodic table are the s-block.

  • The last six columns of the periodic table are the p-block.

  • The middle ten columns of the periodic table are the d-block. Remember that d-block elements fill one energy level late!

    After 3p is filled, 4s is filled, then 3d is filled, and then 4p is filled.

  • The bottom two rows of the periodic table are the f-block. Remember that f-block elements fill two energy levels late!

    After 5p is filled, 6s is filled, then 4f is filled, then 5d is filled, then 6p is filled.


Color code and label your periodic table
Color-code and label your periodic table!



The equation triangle
The Equation Triangle

  • Rule #1 – Write the equation so that it has no division lines.

  • Rule #2 – What is on the left side of the equal sign goes on the top of the triangle.

  • Rule #3 – What is on the right side goes on the bottom of the triangle.



Pure Substance: has characteristic physical & chemical properties that can be used to identify it & has a CONSTANT COMPOSITION

  • Element:

    • Made up of ONE kind of atom (one element from the periodic table of the elements!)

    • Cannot be broken down any further

    • EX: Carbon (C), Nitrogen (N), Oxygen(O), Sodium (Na)

  • Compound:

    • TWO or more atoms chemically combined (molecule)

    • Can be chemically broken down into individual atoms (cannot be physically separated)

    • Definite **ratio of elements** in the compound

    • EX: Water (H2O), Salt (NaCl), sugar (C6H12O6)


Mixture:Made up of TWO or more substances (the proportions of the ingredients can vary) that can be physically separated

  • Homogeneous Mixture:

    • Substances are mixed EVENLY throughout

    • Looks the “same”

    • EX: Sugar Water, Salt Water, Kool-aid

  • Heterogeneous Mixture:

    • Substances are NOT evenly distributed

    • Looks “different” throughout

    • EX: Concrete, Dirt, Pond Water, chocolate chip cookie



How to determine molecular shape

Know the 5 common shapes

How to Determine Molecular Shape

  • 1. Draw the Lewis Diagram.

  • 2. Tally up # of bonding regions and lone pairs on central atom.

    • double/triple bonds = ONE bonding region

  • 3. Shape is determined by the # of bonding regions and lone pairs.



1 linear 180

CO2

1. LINEAR (180°)

2 bonding regions

0 lone pairs


2 trigonal planar 120

BF3

2. TRIGONAL PLANAR (120°)

3 bonding regions

0 lone pairs

Exception to the octet rule! – 6 valence electrons!


3 bent 120

NO2-1

3. BENT (<120°)

2 bonding regions

1 lone pair

BENT

<120°


4 tetrahedral 109 5

CH4

4. TETRAHEDRAL (109.5°)

4 bonding regions

0 lone pairs


5 trigonal pyramidal 107

NH3

5. TRIGONAL PYRAMIDAL (107°)

3 bonding regions

1 lone pair


6 bent 104 5

H2O

6. BENT (104.5°)

2 bonding regions

2 lone pairs



What are the properties of light
What are the properties of light?

  • By 1900 there was enough experimental evidence to convince scientists that light consists of waves.

    • The amplitude of a wave is the wave’s height from zero to the crest.

    • The wavelength, represented by , is the distance between the crests.

    • The frequency, represented by , is the number of wave cycles to pass a given point per unit time.


The electromagnetic spectrum
The Electromagnetic Spectrum

  • The product of frequency and wavelength equals a constant (c), the speed of light.

    c = 

    • The wavelength and frequency of light are inversely proportional to each other.

    • As the wavelength of light increases, the frequency decreases.


Electromagnetic radiation
Electromagnetic Radiation

According to the wave model, light consists of electromagnetic waves.

  • Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays.

  • All electromagnetic waves travel in a vacuum at a speed of2.998  108 m/s.



The visible spectrum
The Visible Spectrum

The sun and incandescent light bulbs emit white

light, which consists of light with a continuous range of wavelengths and frequencies.

  • The wavelength and frequency of each color of light are characteristic of that color.

  • When sunlight passes through a prism, the different wavelengths separate into a spectrumof colors.

  • Red has the longest wavelength and the lowest frequency in the visible spectrum.


Sample problem calculating the wavelength of light
Sample problem: Calculating the wavelength of light

Use the speed of light to calculate the wavelength of yellow light emitted by a sodium lamp if the frequency of the radiation is 5.09  1014 Hz(5.09  1014 s–1).

(contd.)


Sample problem calculating the wavelength of light1
Sample problem: Calculating the wavelength of light

1. Analyze List the knowns and the unknown.Use the equation c =  to solve for the unknown wavelength.

Knowns

frequency () = 5.09  1014/s

c = 2.998  108 m/s

Unknown

wavelength () = ? m

(contd.)


Sample problem calculating the wavelength of light2
Sample problem: Calculating the wavelength of light

2.Calculate Solve for the the unknown.

Write the expression that relates the frequency and the wavelength of light.

c = 

Rearrange the equation to solve for .

Substitute the known values for  and c into the equation and solve.

(contd.)


Sample problem calculating the wavelength of light3
Sample problem: Calculating the wavelength of light

3. EvaluateDoes the result make sense?

The magnitude of the frequency is much larger than the numerical value of the speed of light, so the answer should be much lessthan 1.


The quantization of energy
The quantization of energy

  • Planck showed mathematically that the amount of radiant energy (E) of a single quantum absorbed or emitted by a body is proportional to the frequency of radiation ().

    E  orE = h

    • The constant (h), which has a value of 6.626  10–34 J · s is called Planck’s constant.

    • The energy of a quantum equals h.


Sample problem calculating the energy of a photon
Sample problem: Calculating the energy of a photon

Use Planck’s constant to calculate the energy of a photon of microwave radiation with a frequency of 3.20  1011/s.

(contd.)


Sample problem calculating the energy of a photon1
Sample problem: Calculating the energy of a photon

AnalyzeList the knowns and the unknown.Use the equation E = h to calculate the energy of the photon.

Knowns

frequency () = 3.20  1011/s

h = 6.626  10–34 J · s

Unknown

energy (E) = ? J

(contd.)


Sample problem calculating the energy of a photon2
Sample problem: Calculating the energy of a photon

2. CalculateSolve for the unknown.

Write the expression that relates the energy of a photon of radiation and the frequency of the radiation.

E=hv

Substitute the known values for  and h into the equation and solve.

E = (6.626  10–34 J · s)  (3.20  1011/s) = 2.12  10–22 J

(contd.)


Sample problem calculating the energy of a photon3
Sample problem: Calculating the energy of a photon

3. Evaluate Does the result make sense?

Individual photons have very small energies, so the answer seems reasonable.





Valence Electrons

  • Valence electrons are the number of electrons in the outermost energy level.

  • All elements within a group have the same number of valence electrons

  • These electrons are available to be lost, gained, or shared in the formation of chemical compounds.

  • Found in the s and p orbitals of the highest energy level.

  • Often located in incompletely filled energy levels.


How do I find the number of Valence Electrons?

  • To find the number of valence electrons, underline the largest number as often as it occurs and add the superscripts.

  • Example: Cl – 1s2, 2s2, 2p6, 3s2, 3p5– 7 valence electrons

  • Example: Mg - 1s2, 2s2, 2p6, 3s2– 2 valence electrons

  • Example: Kr – 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6– 8 valence electrons

  • Example: U – 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2, 4d10, 5p6, 6s2, 4f14, 5d10, 6p6, 7s2, 5f4 – 2 valence electrons


Shortcut to finding Valence Electrons!

Group 1 1 valence electronGroup 2 2 valence electronsGroup 13 3 valence electronsGroup 14 4 valence electronsGroup 15 5 valence electronsGroup 16 6 valence electronsGroup 17 7 valence electronsGroup 18 8 valence electrons


WARNING

  • there is no shortcut for finding valence electrons for transition or inner-transition metals

  • The number of valence electrons for elements from Groups 3-12 can have different values based on the conditions of chemical reactions. This is also true for a small number of the metals in Groups 13-16


Reactivity of groups
Reactivity of groups

  • Elements in the same group/family have the same number of valence electrons.

  • If you’ll remember from last class, elements in the same group have the similar physical and chemical properties; they react the same way (think alkali metal demo). This has to do with the number of valence electrons!


Oxidation Numbers

Remember that all atoms want to have a full outermost energy level of 8?.....


Oxidation Numbers

  • The electrical charge resulting from atoms gaining or losing electrons to fill their outermost s and porbitals.

    • All uncombined elements have an oxidation number of zero (0)

    • Metals lose electrons and have (+) oxidation numbers; nonmetals gain electrons and have (–) oxidation numbers

    • All Noble Gases have an oxidation number of zero (0).


Ions

  • Ion – a charged particle or molecule created through the loss or gain of valence electrons

  • Cation – positively charged particle or molecule created through the loss of valence electrons as a result of ionization

  • Anion – negatively charged particle or molecule created through the gain of valence electrons as a result of electronegativity



Summary periodic trends
Summary: periodic trends

15. Explain Periodic TrendsIn general, how can the periodic trends exhibited by the elements be explained?


The Octet RuleAll elements gain or lose electrons so that they end up with the same electron configuration as the nearest noble gas.

  • The Octet Rule is the driving force for chemical reactions and properties.

  • When we say that an atom “wants to” do something, what we really means is that the atom is doing it so that it will become more stable.


Periodic trends1

0

Periodic Trends

  • Periodic Trends– properties that show patterns when examined across the periodic table.

  • Atomic Radius – one half the distance between the nuclei of identical atoms that are bonded together.

  • Ionization Energy– the energy required to remove one electron from a neutral atom of an element.

    • Ion – an atom or group of atoms that has a positive or negative charge

    • Ionization – the process of forming an ion.*** Change the electrons, NOT PROTONS!!!! ***

    • First Ionization Energy –the first electron…

    • Second Ionization Energy–the second electron…

  • Electronegativity – a measure of the ability of an atom in a compound to attract electrons. An uneven concentration of charge.



The Atom

The atom consists of two parts:

1. The nucleus which contains:

protons

neutrons

2. Orbiting electrons.


The Atom

All matter is made up of elements (e.g. carbon, hydrogen, etc.).

The smallest part of an element is called an atom.

Atom of different elements contain different numbers of protons.

The mass of an atom is almost entirely due to the number of protons and neutrons.


Mass number

= number of protons + number of neutrons

A

X

Element symbol

Z

Atomic number

= number of protons


The Atom

The atom consists of two parts:

1. The nucleus which contains:

protons

neutrons

2. Orbiting electrons.


The Atom

All matter is made up of elements (e.g. carbon, hydrogen, etc.).

The smallest part of an element is called an atom.

Atom of different elements contain different numbers of protons.

The mass of an atom is almost entirely due to the number of protons and neutrons.


Mass number

= number of protons + number of neutrons

A

X

Element symbol

Z

Atomic number

= number of protons


238

235

U

U

92

92

There are many types of uranium:

Isotopes of any particular element contain the same number of protons, but different numbers of neutrons.


Modes of decay

0

Modes of Decay


Radioactive Decay

Radioactive decay results in the emission of either:

  • an alpha particle (a),

  • a beta particle (b),

  • or a gamma ray(g).


Alpha Decay

An alpha particle is identical to that of a helium nucleus.

It contains two protons and two neutrons.


A

A - 4

X

Y

+

Z

Z - 2

4

He

2

Alpha Decay

unstable atom

alpha particle

more stable atom


226

222

Ra

Rn

88

86

4

He

2

Alpha Decay


+

A - 4

Y

A

X

Z - 2

Z

4

4

226

222

He

He

Ra

Rn

+

2

2

88

86

Alpha Decay


Beta Decay

A beta particle is a fast moving electron which is emitted from the nucleus of an atom undergoing radioactive decay.

Beta decay occurs when a neutron changes into a proton and an electron.


Beta Decay

As a result of beta decay, the nucleus has one less neutron, but one extra proton.

The atomic number, Z, increases by 1 and the mass number, A, stays the same.


218

218

Po

At

84

85

0

b

-1

Beta Decay


A

A

0

0

b

b

X

Y

+

Z

Z + 1

-1

-1

218

218

Po

Rn

+

84

85

Beta Decay


Gamma Decay

Gamma rays are not charged particles like a and b particles.

Gamma rays are electromagnetic radiation with high frequency.

When atoms decay by emitting a or b particles to form a new atom, the nuclei of the new atom formed may still have too much energy to be completely stable.

This excess energy is emitted as gamma rays (gamma ray photons have energies of ~ 1 x 10-12 J).


Penetrating power of radiation
Penetrating Power of Radiation

  • The most dangerous form of radiation is gamma radiation. The least dangerous is alpha radiation.




Dalton s postulates
Dalton’s Postulates

  • All elements are composed of tiny indivisible particles called atoms.

  • Atoms of the same element are identical. The atoms of any one element are different from those of any other elements.

  • Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds.

  • Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.


Dalton s postulates1
Dalton’s Postulates

  • We now know that certain parts of this theory are invalid.

  • Part 1 – False. Atoms have been split.

  • Part 2 – Partially False. Some atoms of the same element have more neutrons. (However, atoms of different elements are different.)

  • Part 3 – True!

  • Part 4 – True!


Dalton s model
Dalton’s Model

  • Just a tiny ball with no parts inside



J j thomson
J. J. Thomson

  • Used a cathode ray tube to shoot an electrical charge through it.

  • Saw that the particles were deflected towards the positive end of the tube.

    • This must mean that atoms contained a NEGATIVE charge!

  • Discovered the ELECTRON.

http://www.youtube.com/watch?v=IdTxGJjA4Jw

http://www.youtube.com/watch?v=RW_zfKOU9uM


Thomson s model
Thomson’s Model

  • “Plum Pudding” or “Chocolate Chip Cookie Dough” Model.

  • A ball of positive charge containing a number of electrons.



Ernest rutherford
Ernest Rutherford

  • Did the Gold Foil Experiment

    • Shot alpha (positively charged) particles at a sheet of gold foil.

  • Saw that most particles passed through the foil and some deflected straight back at different angles.

  • Means that atoms are mostly empty space but contain a densely packed positive center….

    • Discovered the NUCLEUS

http://www.youtube.com/watch?v=wzALbzTdnc8&NR=1

http://www.youtube.com/watch?v=5pZj0u_XMbc


Rutherford model
Rutherford Model

Dense, positively charged nucleus

Surrounded by electrons (mostly empty space)

Empty Space

Nucleus

Electrons


Niels bohr 1913
Niels Bohr (1913)


Niels bohr
Niels Bohr

  • Electrons travel in definite orbits around the nucleus

  • Electrons are found in “energy levels”

  • AKA Planetary Model

http://www.youtube.com/watch?v=wCCz20JOXXk


Bohr model
Bohr Model

Nucleus

Electrons

(orbiting the

nucleus)



65 39 amu what does this mean
65. 39 amu…What does this mean?

  • The mass of one atom is not exactly the same as the average mass of many

    • Ex.) One atom of Zinc  65.39 amu

      • This is just the average of the masses of Zn-65, Zn-64, and Zn-66


Calculating average atomic mass
Calculating Average Atomic Mass

  • For each isotope:

  • Multiply

    percent abundance X mass number

  • Then Addtogether the values for each of the isotopes


Example
Example

  • Copper has two naturally occurring isotopes: Copper-63 (69.17%) and copper-65 (30.83%). Calculate the average atomic mass of copper if the relative masses of the isotope are Copper 63 (63 amu) and copper-65 (65 amu).



Physical properties
Physical Properties

  • Can be observed or measured without changing sample’s composition

    Examples:

    Solubility in water

    Volume

    Length

    Color

    Odor

    Melting/Boiling point

    Mass

    Density

    Viscosity


Chemical property
Chemical Property

  • Substance’s ability to undergo changes that will change into a new substance

    Examples:

    flammability

    combustibility

    ability to react with oxygen

    ability to neutralize acids

    ionization


Extensive property
Extensive Property

  • Depends on the QUANTITY of matter

    • Examples:

      • Mass

      • Volume

      • Length

    • These Properties change when something gets “fatter”


Intensive property
Intensive Property

  • Does NOT depend on the quantity of matter. (It depends on the COMPOSITION of it)

    • Examples:

      • Density

      • Temperature

      • Color

      • Conductivity

    • These Properties DON’T change when something gets “fatter”


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