Ch. 5 Atomic structure and PT.pptx

Chemistry

Chapter 5 & 13 –

Atomic Structure &

The Periodic Table

What do you know about the

atom? The parts it is made of? Its

size?

5.1

Early Models of the Atom

1. All elements are composed of tiny indivisible

particles called atoms.

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

3. Atoms of different elements can physically combine with one another in simple whole-number ratios to form compounds.

Atom – the smallest particle of an element that retains the properties of that element .

Example: How many atoms are in each compound?

CO_{2 3} H₂O H₂SO_{3 4 7}

5.2 Structure of the Nuclear Atom

• negatively charged subatomic particle. They have a –1 charge and are 1/1840 the mass of a hydrogen atom

Cathode Ray Tube (CRT)

• device used to originate a flow of charged particles

J.J. Thomson

- credited with

discovering the electron

• _{He used CRT's to measure deflection of charged rays} using different gasses, magnets, and different metal electrodes.

• _{Found that the ray moved from the anode (-) to the} cathode (+)

• _{He proposed that the ray was composed of negatively} charged particles which he called electrons.

Take a few minutes to

summarize Thomson’s

Robert Millikan

–

•

Proton – positively charged

Neutron

- discovered by James

Chadwick 1932.

• _{Has approximately the same}

mass as a proton.

• _{They are located in the}

nucleus.

Match the following scientist and their accomplishments. a. Dalton

b. Thomson c. Millikan d. Chadwick

__ oil drop experiment and the properties of the electron __ discovered the proton and its location

__ used the cathode ray tube to discover the electron __ said particles are indivisible

Once subatomic particles had been

discovered, Dalton’s model of the

Thomson proposed the

“Plum Pudding” Model of the

atom.

Rutherford – credited with discovering

the nucleus.

Nucleus – the central core of an atom and is composed of protons and neutrons.

5.3

Distinguishing Between Atoms

Atomic Number

– the

number of protons in

Example:

•

What is the atomic number for the following

elements?

Al

C Br I Na Ag

•

How many protons are there in each?

13 6 35 53 11 47

• _{Mass Number}

• _Isotopes

– the number of protons and neutrons in the nucleus of an atom.

Example:

• _{What is the number of neutrons in each of the}

following isotopes?

27_Al 12_C 80_Br 127_I 23_Na 108_Ag

14 6 45 74 12 61

If protons + neutrons =mass number, then how many neutrons are present in an atom

Element _NumberAtomic _NumberMass # protons # electrons # neutrons

12

25

6

6

K

40

23

28

Mg

12

12

13

C

6

12

6

19

19

19

21

Bellwork

HW Check

Element

Name Mass # Atomic # # protons # electrons

# neutrons

(use the isotope listed)

Sc

Scandium 45 From PT = Atomic # = protons

= mass-protons Cd Cadmium 112 Xe Xenon 131 S Sulfur 32

How many total atoms are in the following compounds? H₃CO₃ _____ HF _____ C₄H₆OH ______

NH₃______ Fe₂O₄ ______

7

2

12

Bellwork: Friday, September 21

In our class, tests are 50% of your grade, labs are 25%, and daily grades are 25%. If you

have the following averages, what is your overall grade in Chemistry?

Homework:

Use your notes

to fill in the

crossword

Across

1. Scientist that discovered 4 down

3. Model for an atom that Thomson proposed 6. Positively charged sub-atomic particle 8. Measurement unit for atomic mass 9. Proposed the first atomic theory 11. CRT for short

12. Negatively charged sub-atomic particle 13. = protons + neutrons

14. = protons Down

2. The masses on the periodic table are decimals because they are calculated as a ________ ___________

4. Sub-atomic particle with the same mass as a proton 5. Scientist that used the oil drop experiment

7. Performed the gold foil experiment

10. Scientist credited with discovery of the electron

Atomic Mass

–

element.

Example:

A sample of cesium is 75%

Cs, 20%

Cs,

and 5%

Cs.

Calculate its average atomic mass.

0.75 x 133 = 99.75

Compare this value to that of the

periodic table. Is it accurate?

132.85 amu

Calculated Value

132.905 amu

Periodic Table

Chemistry

The Evolution of Atomic

Models

The work of Dalton, Thomson and

Rutherford began an age of exploration that culminated with a model of the atom that described a dense nucleus

Bohr model

-

Electrons are arranged

in concentric circular

paths (orbits) around

the nucleus

Called the planetary

model

Electrons have

Quantum mechanical model

It comes from the mathematical solutions to the

Schrodinger equation

The probability of finding an electron within a

certain volume of space surrounding the nucleus

can be represented by a cloud (electron cloud)

The cloud represents where the electron can be

found approximately 90% of the time.

Energy level

- region around the nucleus where the

electron is likely to be moving.

Quantum

- the amount of energy required to

move an electron from its present

Atomic orbital – the region in

space where the electron is likely

to be found

A quantum mechanical model of a hydrogen atom, which has

one electron, in its state of lowest energy. The varying density of the spots indicates the relative likelihood of finding the

Electrons can be described

by a series of 4 quantum

numbers

.

1.

Principle quantum number (n)

-describes the principal

energy level

an

electron occupies

-values of 1,2,3,4,etc

2. Azimuthal quantum number (

l

)

-describes the

shape

of atomic orbitals

-s orbitals are spherical, p orbitals are

peanut shaped, d orbitals are daisies

and f orbitals are fancy

-designates a sublevel

Where do I find the orbital shapes?

S

P

D

4s 3s 2s 1s 2p 3p 3d E N E R G Y

n l m_l m_s 1 0(s)

2 0(s) 1(p)

0 0 -1, 10

, 3 0(s)

1(p) -1, 100 , 2(d) -1, 1

, 0

,

-2, 2 4 0(s) 0

Electron configuration –

Describes ways in which

electrons are arranged around

1. Aufbau principle-

States that electrons

enter orbitals of lowest

energy first.

2. Pauli exclusion principle

3. Hund’s rule-

When electrons

Complete the orbital diagrams below.

1s 2s 2p 3s

H _ _ _ _ _ _

He _ _ _ _ _ _

O _ _ _ _ _ _

Quick and Easy Electron Configuration

S

P

D

F

First, number the periods 1-7, 3-6 and 4-5 as shown by your teacher.

1 2 3 4 5 6 7 3 4 5 6 4 5

Now, lets try to do an electron configuration for carbon.

Begin with the first quantum number and use the periodic table to write the configuration.

Now, try the three in your notes. He

Na Ti

For a shorter way to write electron configuration, write the nearest noble gas and then continue. AKA “Shorthand Notation”.

Ex: Ti can be written as OR

Use “Shorthand Notation” to write these electron configurations

6. Al

7. K

8. Fe

9. Co

Bellwork

Wednesday, January 12

• _{What would be the value of the principal quantum}

number for the following elements?

• _Na • _Sn • O

• _Zr

• _{Draw an orbital that matches each of the following}

azimuthal quantum numbers.

Homework Check

• _{Calculate the weighted average mass of the element chlorine}

that has the following isotopes

35_{Cl (75.77%)} 36_{Cl (0.01%) and} 37_{Cl (24.23%)}

• _{Write the full electron configurations for the following:}

1.Ti ___________________________________________ 2.Si ___________________________________________ 3.Ag ___________________________________________

Bellwork

Write the electron configurations of these elements on your bellwork sheet.

1. F

2. Ca

Homework Check

•_{An electron moves from energy level 1 to energy level 4 in an}

atom. To do this, energy would need to be (circle one) absorbed / released. How many quanta of energy does this change involve? _______________________

•_{Draw one of the shapes that correspond to each azimuthal}

quantum number below.

l = “0” l = “1” l=”2”

•_{Match the elements listed to their description on the left.}

_____ Located where n = 3. A. Iron

_____ Outer electrons have a spherical shape B. beryllium

Electromagnetic radiation - a

series of energy waves that

includes radio waves,

microwaves, visible light,

infrared and ultraviolet light,

X-rays, and gamma rays.

We can

measure not

only the

length of

each wave of

light, but

also its

Parts of a wave:

Amplitude Draw

amplitude- height of the wave

from the origin to the crest

wavelength -



- distance

between the crests

frequency -



- the number of

wave cycles to pass a given point

per unit of time.



= c/



where c = speed of light

c= 3.00 x 10

m/s

Ex. A certain wavelength of yellow

light has a frequency of 2.73 x

10

s

. Calculate its wavelength.



= c/





= c/





= 3.00 x 10

m/s

2.73 x 10

s

Spectrum

- series of colors

produced when sunlight is

separated by a diffraction gradient.

R

O

Y

G

.

B

I

V

Red: has the longest wavelength,

lowest frequency  Lowest

energy

Violet: has the shortest

Atomic emission spectrum

Demo!

Max Planck believed that energy was emitted or

absorbed by small units called quanta. He found

that the amount of energy released or absorbed

was proportional to the frequency of the

radiation.

E = h

ν

E

= Energy

ν

= frequency

h

= Planck’s constant: 6.63 x 10

J∙s

Einstein proposed that

electromagnetic radiation

can be viewed as a stream

of particles called

photons

.

His famous equation, E =

mc

helped to determine

the amount of energy

Example: Calculate the energy of an

individual photon of yellow light

having a frequency of

2.73 x 10

s

.

E = h



E = (6.63 x 10

J

s )(2.73 x 10

s

)