unit 4: electron configuration, periodic trends and ... · pdf filethis is the electron...

Do Now:

Pick up sheets by the door (note

packet and homework packet if you

didn’t pick one up last week)

Take out completed homework #1

Take out Atoms Book

Review before the quiz

_____1) Bohr’s model of the atom says that electrons

a) are mixed in evenly with positive charge

b) are found orbiting a positively-charged nucleus

c) are found orbiting a positively-charged nucleus in energy levels (shells)

d) are found in regions of probability around the nucleus called orbitals

Review Before the Quiz

_____5) Dalton’s model of the atom

states that atoms

e) have positive particles called protons

and negative particles called electrons

f) have a positively-charged nucleus

g) have a positively-charged nucleus with

electrons in energy levels (shells)

h) are hard solid indivisible spheres

Review Before the Quiz

One model of the atom states that atoms are tiny particles composed of a uniform mixture of positive and negative charges. Scientists conducted an experiment where alpha particles were aimed at a thin layer of gold atoms. Most of the alpha particles passed directly through the gold atoms. A few alpha particles were deflected from their straight-line paths. (This question was taken directly from a Regents Exam).


Most of the alpha particles passed

directly through the gold atoms

undisturbed. What does this evidence

suggest about the structure of gold

atoms?

Atoms are mostly empty space


A few of the alpha particles were

deflected. What does this evidence

suggest about the structure of the gold

atoms?

The nucleus must be positive since it

deflects positively charged alpha

particles

Quiz-E-Poo time

9.5 minutes

Can use your notes/atom book. Turn

ALL OF IT IN when you are done

Atom Book

Homework

Quiz

Quiz

Name

Answers ¼ sheet of paper

Name that model!

1) Atoms look like solid spheres

2) Atoms are mostly empty space

3)Electrons are found in distinct levels similar

to the path of planets around the sun

4) The most ‘up-to-date’ model

5) The first model to include electrons

Objective

Describe the difference between a full

and an occupied energy level

What is an energy level?

When is it full?

I. The Bohr Atom

Bohr was the first to propose that the

electrons were located in energy levels

A lower case “n” is used to denote

these principle energy levels (also

called principle quantum numbers).

The level closest to the nucleus is

labeled n = 1. The next level is labeled

n = 2 and so forth.

I. The Bohr Atom

Each principle energy level had a certain

energy value associated with the level.

The closer the level was to the nucleus,

the lower the energy of the level.

I. The Bohr Atom

As long as the electrons were in these

levels, the electrons do not give off

energy.

Number the principle Energy levels

1

2

3

4 5

2. Electron Configuration and the

Periodic Table

Each principle energy level can only

hold so many electrons before the level

is full.

A quick and easy way to determine the

maximum number of electrons (max e-)

that a principle energy level can hold is

given by the following:

max e- = 2 n2.

First square the principle energy level

number (n) then multiply by 2

2n2 Trick

Principle Energy

Level (n)

Maximum

Electrons

1

2

3

4

5

6

2

8

18

32

50

72

Electron Configuration

Electrons are arranged around the

nucleus by filling up the first principle

energy level (n=1), then the second

energy level, etc. (with some exceptions

that we will get to later in the unit…)

This is the electron configuration given

on your periodic table.


The number of electrons

are listed for each level with

a dash between levels:

for oxygen (O) which has a

total of 8 electrons, the

configuration is 2–6


2 electrons are located in

the first principle energy

level

6 electrons are located in

the second principle

energy level.

Look up the electron config. on

the PT for the element given &

fill in the chart.

Element n = 1 n = 2 n = 3 n = 4

Ca 2 8 8 2

Na

F

B

2 8 1

2 7 2 3

Look up the electron config. on

the PT for the element given &

fill in the chart.

Element n = 1 n = 2 n = 3 n = 4

Al

C

H

Side Bar: Look up # 72 Hf

What does the ** mean?

So the electron configuration of Hf is…..

2-8-18-32-10-2

What is the electron configuration of gold (Au)

# 79?

2-8-18-32-18-1

ADDITIONAL INFORMATION

Ions: atoms with a charge because of

gaining or losing an electron

Gained an electron (-) charge

Lost an electron (+) charge

How would an Ion’s configuration

compare to a neutral atoms?

Ion Electron configuration

Al Configuration :

Al+3 Configuration:

Na Configuration:

Na+1 configuration:

Cl configuration:

Cl-1 configuration:

Ion Configuration

Negative charge gained that many

more electrons

Positive charge lost that many

electrons

Completely Filled vs. Occupied Principle

Energy Levels

Is this room occupied?

Is this room filled?


Energy Levels

Occupied means that

there is at least one

electron in the Principle

Energy Levels (PEL)

Li: 2 – 1 has 2 occupied

PELs


Energy Levels

Completely Filled means that each level has its maximum number of electrons which can be determined by the 2n2 rule.

n =1 then 2(1)2 =2

& n = 2 then 2(2)2=8

Li: 2 – 1 has only 1 Completely Filled PEL

To help you review the 2n2 rule

complete the following chart

PEL

(n)

1 2 3 4 5 6 7

Max

e- 2 8 18 32 50 72 98

In the chart:

Copy the electron configuration from the

Periodic Table

Determine the number of Occupied

Principle Energy Levels (PEL)

Determine the number of Completely

Filled Principle Energy Levels

Max e-: 2-8-18-32-50-72-98

Elemen

t

Electron Conf. #

ocup

p

#

compl

filled

C 2 1 2-4

Max e-: 2-8-18-32-50-72-98

Elemen

t

Electron Conf. #

ocup

p

#

compl

filled

Na

O

Cl

2-8-1

2-6

2-8-7

3 2

2 1

3 2

Max e-: 2-8-18-32-50-72-98

Elemen

t

Electron Conf. #

ocup

p

#

compl

filled

He

F

Ne

2

2-7

2-8

1 1

2 1

2 2

Max e-: 2-8-18-32-50-72-98

Elemen

t

Electron Conf. #

ocup

p

#

compl

filled

Si

Zn

Au

2-8-4

2-8-18-2

2-8-18-32-18-1

3 2

4 3

6 4

Ticket out

How many full energy levels are there in

an atom of Gold (Au)?

Done: Do homework #2, all except the

last problem

Do Now

Take out your notes packet (page 4)

Read how to draw bohr diagrams and

attempt the first box (For F: Atomic #__)

OBJECTIVE: Draw accurate bohr

models of atoms

3. Drawing Bohr Diagrams of

Atoms:

1) A circle is used for the nucleus- the

# protons (# p or +) and the # of

neutrons (#n) are placed in the circle.

2) A ring is drawn around the nucleus

for each energy level.

3) The electrons for each energy level

are placed in pairs symmetrically

around the nucleus

For Fluorine (F)

atomic # = _________

atomic mass = ______

electron configuration:

__________________

_

# p =

______________

# n

=_______________

For Aluminum (Al)

atomic # = _________

atomic mass = ______


__________________

# p =

______________

# n

=_______________

Going Backwards:

Determining the identity

of an element from the

Bohr diagram:

# p = _____________

# n =______________

atomic # = _____________

atomic mass = # p + # n =

________________


_______________________

Isotopic Notation:

To review:

To draw a Bohr Model:

Look up the atomic #, atomic mass & the electron configuration

Determine the # of neutrons (atomic mass-atomic #)

Draw nucleus & write the # p & #n in nucleus

Draw rings around the nucleus equal to the # of PEL in atom (# of numbers in electron configuration)

Place electrons for each level symmetrically in the rings in pairs

Going Backwards writing Isotopic

Notation:

# of protons = atomic number so look up the

atomic # to get symbol

Add the # of protons and neutrons to get the

atomic mass (mass #)

Atomic mass is the top number

10Ne20

Atomic # is the bottom number

Now it is your turn!

Complete the Bohr

Model worksheet.

When done, show

me and turn in.

If not done, it

becomes

homework along

with homework #2.

unit 4: electron configuration, periodic trends and ... · pdf filethis is the electron...

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