Mrs Rodriguez

Ch 4The Atom

On the first right side page (after Ch 3 notes):

• Create a Cover page.

• Title: “Ch 4.1-4.5 & 4.8-4.9 Notes”.

• Make atom design the whole page and label the parts

of the atom.

• Include COLOR!

• I have a sample cover page on the next slide you can

choose from or CREATE YOUR OWN DESIGN

(BONUS).

On the back side of cover page (left side),

• Paste in the “I can” Learning Objectives #10-22.

Ch 4

Cover page

Sample Cover Pages

Make design the whole

page about the atom.

Include COLOR!

You can choose this one

OR

CREATE YOUR OWN

DESIGN (BONUS).

TN Ch 4.1-4.2Title and

Highlight

Topic:

EQ:

NOTES:

Write out the notes from my website.

Use different types of note-taking method

s to help you recall info (different color pe

ns/highlighters, bullets, etc)

When I lecture we will add more info, so

LEAVE SPACES in your notes

Summary:

2-3 sentences… What did you learn today

from the notes?

WRITE SUMMARY AT THE VERY END

OF THE NOTES.

Right Side – NOTES ONLY

Question

for

teacher:

After

reading the

notes,

write a

question

that you

have to

ask me so I

may

answer it

doing

lecture

TN Ch 4.1-4.2

Title and

Highlight

DRAW ANY PICTURES, CHARTS,

FIGURES, etc.

WRITE OUT ANY PRACTICE

PROBLEMS/QUESTIONS.

(LEAVE SPACES FOR ANSWERS)

WHEN YOU WATCH MY VIDEO

NOTES ON MY YOUTUBE

CHANNEL, YOU WILL ANSWER THE

PRACTICE PROBLEMS.

**If you have any questions about the

practice problems, please make a note

to ask me I class.

LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC

Topic: Atomic Theory

EQ: Explain the history &

the discovery of the atom

Ch 4.1-4.2

Democritus – The Early Atom

As early as 400 B.C., Democritus

called nature’s basic particle the

“atomon” based on the Greek word

meaning “indivisible”.

– His theory: Matter could not be

divided into smaller pieces fore

ver, eventually the smallest pos

sible piece would be obtained.

Democritus – The Early Atom

▪To Democritus, atoms

were small, hard particles

that were all made of the

same material but were

different shapes and sizes.

▪Atoms were infinite in

number, always moving

and capable of bonding

together.

Democritus vs Aristotle

• Most influential philosopher, Aristotle rejected Democritus’ atom theory because different from his ideas.

• Criticized Democritus’ idea that atoms moved through empty space.

• Aristotle succeeded Democritus and did not believe in atoms. Instead, he thought that all matter was continuous. It was his theory that was accepted for the next 2000 years.

Aristotle

Aristotle favored the earth,

fire, air and water

approach to the nature of

matter.

In the end….. Aristotle was

wrong in the end.

Why?....

John Dalton’s

Atomic Theory

• John Dalton (1766-1844)

• English Chemist and

schoolteacher

• In 1808,performed a

number of experiments

that led to the idea of

atoms…..over 2000 years

later after Democritus &

Aristotle theory.

John Dalton’s Atomic Theory

1. All matter is composed of extremely small particles called atoms.

2. Atoms of a given element are identical in size, mass, and other properties.**

3. Atoms cannot be subdivided, created, or destroyed.**

4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds.

5. In chemical reactions, atoms are combined, separated, or rearranged.

**Today, we know these parts to be wrong!!

Watch video and enjoy!

John Dalton’s Atomic Theory

Was Dalton’s theory a huge step toward our

current model of matter?

– Yes!!! It was a breakthrough in our

understanding of matter.

Was all of Dalton’s theory accurate?

– No!!!

Flaws of Dalton’s Theory…

#2. Atoms of a given element are identical in size, mass,

and other properties.

#3. Atoms cannot be subdivided, created, or destroyed.

Isotopes – atoms with the same

number of protons but a different

number of neutrons

Subatomic particles – electrons,

protons, neutrons, and more

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).

Topic: Subatomic Particles

EQ: Explain the history & the

discovery of the 3 subatomic

particles in anatom

Ch 4.3

Discovery of the Subatomic Particles

The discovery of the subatomic

particles came about from the

study of electricity & matter.

Benjamin Franklin’s kite experime

nt in 1752 demonstrated that

lightning was electrical.

Discovery of the Electron

1870’s - many experiments were performed in

which electric current was passed through gases

at low pressures

These experiments were carried out in glass

tubes called cathode-ray tubes.

Electric CurrentElectric Current

Draw this with n

otes in color!!!

Discovery of the Electron

• The rays traveled from cathode (negative) to anode (positive).

• Negatively charged objects deflected the

rays away.

• Therefore, it was determined that the particles making up the cathode rays were negatively charged.

Thomson’s Plum Pudding Model

In 1897, the English

scientist J.J. Thomson

provided the first hint

that an atom is made of

even smaller particles.

(1908 Nobel Prize in

Chemistry)

Discovery of the Electron

Click on picture to watch video about experiment – will do in class

Thomson’s Plum Pudding Atomic Model

Thomson believed

that the electrons

were like plums

embedded in a

positively charged

“pudding,” thus it was

called the “plum

pudding” model.

Draw this with notes in color!!

Thomson’s Plum Pudding Model

● J.J. Thomson is the first

individual to succeed in

deflecting the cathode ray

with an electrical field, in

1897. The cathode ray is

deflected from a straight

line path by a magnetic

field

● The cathode rays bend

toward the positive pole,

confirming that cathode

rays is negatively

charged.

● Cathode rays were

negatively charged.

Thomson’s Plum

Pudding Model

● J.J. Thomson also determined for a single cathode ray particle the charge to mass ratio. He concluded, comparing to other known ratios, that the mass of the charged particle was much less than Hydrogen (the lightest element).

● Making the atom NOT the smallest particle proving Dalton wrong.

Summary of Plum

Pudding ModelSo….. J. J. Thomson

discovered the electron.

– Atoms are breakable

– found that e- are

negatively charged.

– e- are much smaller and

lighter than atoms.

– every element (atom)

has e-.

He proposed that atoms must

contain + charge that

balanced the - charge of

electrons and make the atom

NEUTRAL.

Robert Millikan (1909):

Millikan’s Oil-drop ExperimentMillikan, provided the first definitive proof that

electric charge is made up of elementary indivisible

quantities and proved the charge of the electron.

• Discovered the mass and charge on the electron

• Charge of electron: -1

• Mass of electron = 9.1 x 10-28 g (which is 1/1840

mass of a hydrogen atom)

• Millikan won the 1923 Nobel Prize for Physics.

Click on picture to watch video about experiment – we will watch in class

Rutherford’s Gold

Foil Experiment

1911 – English physicist

Ernest Rutherford

Rutherford’s experiment

involved firing a stream

of tiny positively

charged alpha particles

at a thin sheet of gold

foil (2000 atoms thick)

In search of giants: Dr. Brian Cox SciTeckUK

Click on picture to watch video about experiment – we will watch in class

Alpha particles

and the Gold foil

●Gold nuclei have a charge

of +79

●Alpha particles have a

charge of +2

●Positive charges repel each

other

●Particles that are reflected,

must be hitting something

dense enough to not absorb

α-particles

●Some α-particles were

deflected at large angles,

and some bounced off the

gold foil.

Observations of Gold Foil Experiment

● Most of the alpha particles passed straight through the gold foil.

● Some of the alpha particles got deflected by very small amounts.

● A very few get deflected greatly.

● Even fewer get bounced off the foil and back to the left.

● Indicated the presence of a center that was positive and sm

all. Proving Thomson wrong about his plum pudding model.

Draw this with

notes in color!!!

Conclusions of Gold Foil

ExperimentSo…..the center region of the atom was named nucleus.

● The atom is 99.99% empty space. ● The nucleus contains a positive

charge ● Nucleus has most of the mass of the

atom. ● Nucleus is approx.100,000 times

smaller than the atom (very tiny). ● The electron cloud region is the

majority of the volume in the atom.● Therefore, the nucleus is very

dense.

Opposites

AttractSO……. atoms are neutral:

• the positive (nucleus) balances out the negative electrons

So, why do electrons stay surrounded around the nucleus?

• “Opposites attract”• Positive and negative electrical

charges attract each other.

• Positive–positive and negative–negative charges repeleach other.

• Positive and negative charges cancel each other so that a proton and an electron, when paired, are charge-neutral.

Draw this with notes in color!!!

Rutherford’s

Model of the Atom

Draw this with

notes!!!

James Chadwick

(1932)• Observed that the atomic

number (# of protons in

the nucleus which equals

the positive charge of the

atom) was less than the

atomic mass.

• Protons accounted for ½

mass of atom

• Since electrons have

almost no mass, it

seemed that something

besides the protons in

the nucleus were adding

to the mass.

Chadwick’s Experiment

Click on picture to watch video about experiment – we will watch in class

The Neutron was

discovered…● Chadwick repeated

the experiments but with the goal of looking for a neutral particle: one with the same mass as a proton, but with zero charge.

● Research continued because there was still about ½ of the mass of the atom missing.

The Neutron was

discovered…● His experiments were

successful. He was able to determine that the neutron did exist and that its mass was about 0.1 percent more than the proton’sand was neutral in charge.

● The neutron accounted for the missing mass (1/2) of the atom.

● Protons and neutrons have about the same mass!

NOVA – atomic modelClick on picture to watch video – we will watch in class

Where are we today in terms of

studying the atom?

Particle accelerators

1. Fermi Lab outside of Chicago

http://www.fnal.gov/

2. Hadron Collider - Switzerland/France

http://public.web.cern.ch/public/en/LHC/LHC-en.html

http://www.youtube.com/watch?v=_fJ6PMfnz2E

http://www.wimp.com/largehadron/3. Berkeley’s Accelorator in California

http://www-afrd.lbl.gov/afrd.html

4. Brian Greene – Elegant Universe

http://www.pbs.org/wgbh/nova/elegant/program_d.html

Click on the links to see more….

Democristus

400BC

Aristotle

4 elements

Dalton (1803)

Atomic Theory

Thomson (1897)

Plum Pudding Model

Cathode Ray Tube

electrons

Rutherford (1911)

Gold Foil Experiment

Proton & Nucleus (Mass and Volume)

Millikan (1909)

Charge & Mass

of electron

Chadwick (1932)

Neutron

THE ATOM - TIMELINE Draw this left side!

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).

Topic: Structure of

the atom

EQ: What is the difference between

protons, neutrons, and electrons?

Ch 4.4

ATOM - “Building Blocks of Matter”

An atom is the smallest particle of an element that retains the chemical properties of that element.

• There are about 118 different elements.

How small is an atom?

Copper atoms in penny:

29,000,000,000,000,000,000,000 (2.9 x 1022)

The Structure of the Atom

The atom is composed of two main regions:

the nucleus & the electron cloud.

The Structure of the Atom

The atom is made up of 3 subatomic particles.

Draw this with

notes in color!!!

Nucleus

Nucleus- VERY small region located at the center of the atom.

The nucleus accounts for most of an atoms mass but very little volume, making it a very dense region.

The nucleus contains protons & neutrons.

proton = p+

neutron = no

Electron

Cloud RegionThe electron cloud is

the negatively

charged region of the

atom that accounts

for most of the atom’s

volume but very little

of the atom’s mass.

The electron cloud is

composed of

electron = e-

Subatomic ParticlesDraw this

Left side!!!

Particle Symbol Location Electrical

charge

Mass

(amu)

Actual

Mass (g)

Electron e- Outside

nucleus

-1 1/1840 9.11x10-28

(About 2000

times smaller

than Proton

and neutron)

Proton p+ Nucleus +1 1

1.67x10-24

Neutron n0 nucleus 0 1

1.67x10-24

They have the SAME Mass

Practice Problem #1

Write both questions and

answer.

1. What are the two main

regions of the atom?

2. What is the charge on

the nucleus?

left side!!!

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).

Topic: Element names, symbols,

and the structure of the atom

EQ: How do you write an element’s

symbol? How many p+, no, & e- does

any element have?

Ch 4.5

Chemical

Symbols

Chemists use chemical

symbols to represent elements.

• The chemical symbol consists

of 1 or 2 letters.

The first letter ALWAYS

______________.

•The next letter is ___________.

capitalized

lowercase

Origins of the Names

of the Elements

Most chemical

symbols are based o

n the English

name of the

element.

Some symbols are

based on Greek or

Latin names, which

include the following:

Read!!

Periodic Table

The periodic table of the elements lists all known elements

according to their atomic numbers = # of protons.

How do you read the PERIODIC TABLE?

Draw with notes!

Atomic number & Symbol

The # of protons found

in the nucleus

AND

The # of electrons

surrounding the nucleus.

An abbreviation of the

element name.

Atomic weight vs Mass Number

Average weight of all the

isotopes.

Mass Number:

Rounded WHOLE NUMBER

= # of protons and # of

neutrons in the nucleus.

Atomic weight – 12.01

Mass number - 12

Symbol Notation

XMass

number

Atomic

numberSubscript →

Superscript →

Symbol NotationRounded whole number from at

omic weight listed on P.T.

Mass# = p+ + no

# of neutrons = mass number – # p+

A is always the larger

number than Z.

Protons determine the identity of

the element.

Atomic # = p+ = e- (atoms are neutral)

Look for the element chlorine…..

Let’s write his chemical symbol notation

Cl35

17

NUMBER OF P

ROTONS

# PROTONS+

# NEUTRONS

Mass Number

Atomic Number

Practice

Problem #1Write the questions and answer.

• What is the charge on a sodium (Na) atom?

• What is the charge on a Na nucleus?

• What is the atomic number of potassium (K)?

• How many protons are in the nucleus of a potassium atom?

• How many electrons are in the potassium nucleus?

left side!!!

Practice Problem #2

left side!!!

Element Atomic # Mass # p + n o e - Symbol

Oxygen 8

33 42

31 15

91 140

Sodium 23

Uranium 238

80Br

35

26

Write out the chart. Using the P.T., fill in the missing information.

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).

Topic: Isotopes

EQ: What is an isotope and how

does it affect the atom?

Ch 4.8

Isotopes: When the Number of Neutrons Varies

There is not just one type of each atom, there are several.

Isotopes – different version of the SAME element.

Same: Element name, atomic number, # of protons

Different: Mass number and # of neutrons

Isotopes

How to write

Isotope Notation?

For instance:

• Carbon has several isotopes & is distinguished by its mass #

• Carbon-12, Carbon-13, Carbon-14

Isotope Notation:

• Element – Mass #

• 12C = carbon – 12 = C-12

EXAMPLE OF AN ISOTOPE

Cl35

17 Cl37

17

20 NEUTRONS

Mass Number

18 NEUTRONS

ATOMIC NUMBER

Chlorine - 35 Chlorine - 37

Practice Problem #1

Naturally occurring carbon consists of three i

sotopes: 12C, 13C, and 14C.

State the number of protons, neutrons, and

electrons in each of these carbon atoms. 12C 13C 14C6 6 6

#p+ _______ _______ _______

#no _______ _______ _______

#e- _______ _______ _______

Isotope_______ _______ _______

Notation

left side!

Practice Problem #2left side!

Circle which of the following are isotopes.

40

20 X 40

18 X 42

20 X 40

19 X 43

20 X

Who is this element?

Practice Problem #3left side!

Consider the following pairs.

Does either pair represent a pair

of isotopes? Explain.

a.2311Na and 24

11Na

a. 2411Na and 24

12Mg

Practice Problem #4left side!

Determine the number of protons, neutrons

and electrons in the isotopes of the

following atoms:

88

38 Sr 84

38 Sr

Practice Problem #5left side!

Write the atomic symbol (AZX)

for each of the following isotopes.

1. Z = 8, number of neutrons = 9

2. The isotope of chlorine in which A =

37

3. Z = 27, A = 60

4. Number of protons = 26, number of

neutrons = 31

5. The isotope of I with a mass numbe

r of 131

6. Z = 3, number of neutrons = 4

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).

Topic: Average Atomic Mass

EQ: How do you calculate average

atomic mass?

Ch 4.9

Average Atomic

Mass

The atomic masses

listed in the Periodic

Table are a

“weighted average”

of all the isotopes of

the element.

Units:

Atomic mass unit

(amu)

Natural Abundance

All elements have their own unique

percent natural abundance of isotopes.

• Natural abundance refers to the

abundance of isotopes of a chemical

element as naturally found on a planet.

Naturally occurring chlorine consists of

75.77% chlorine-35 (mass 34.97 amu) and 24.23% chlorine-37 (mass 36.97 amu).

Which isotope is the most abundant?

What is the Average Atomic Mass of Cl?

Calculating Average Atomic Mass

In general, average atomic mass is calculated

according to the following equation:

Step 1: Convert the percent natural abundances into

decimal form by dividing by 100.

Step 2: Multiply the decimal abundances with the

isotopes mass.

Step 3: Add up the atomic masses for each isotope.

This is the average atomic mass for that element

(should be close to the number listed on P.T.)

Natural Abundance

Naturally occurring chlorine consists of

75.77% chlorine-35 (mass 34.97 amu) and 24.23% chlorine-37 (mass 36.97 amu).

What is the Average Atomic Mass of Cl?

Practice Problem #1Gallium has two naturally occurring isotopes:

Ga-69, with mass 68.9256 amu and a natural

abundance of 60.11%, and Ga-71, with mass

70.9247 amu and a natural abundance of

39.89%. Calculate the atomic mass of gallium.

Left side: Leave 5 lines of space to solve in class

Practice Problem #2Naturally occurring bromine molecules, Br2 have

masses of 158, 160. and 162amu. They occur in th

e relative abundances 25.69%, 49.99% and 24.31

% respectively. What is the average atomic mass o

f bromine molecules?

Left side: Leave 5 lines of space to solve in class

Practice Problem #3Naturally occurring lead is found to have the

following isotopic relative abundance. 204Pb 3.0%, 206Pb 24%, 207Pb 20.% and 208Pb 53%.

Calculate the average relative atomic mass of Pb

from the data.

Left side: Leave 5 lines of space to solve in class

Summary:

Let’s reflect….

What did you learn today from the notes?

(2-3 sentence)

WRITE SUMMARY AT THE VERY END

OF THE NOTES (right side).