- 151 Views
- Uploaded on

Download Presentation
## PowerPoint Slideshow about ' Isotopes' - fuller

**An Image/Link below is provided (as is) to download presentation**

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Isotopes

They are atoms of the same element that have different numbers of neutrons.

0

What Are Isotopes?It’s just a change in the neutrizzle fo shizzle!!!

There are 3 different “versions” of a hydrogen atom

0

An ExampleNote how the number of

protons never change!!!

There are 3 different “versions” of a hydrogen atom

0

An ExampleHaving more neutrons

increases the mass

There are 3 different “versions” of a hydrogen atom

0

An ExampleMass number = 1

Mass number = 3

Mass number = 2

Why does The atomic mass on the periodic table have so many decimal Places?

6

C

12.01115

13

Al

26.982

10

Ne

20.180

Atomic mass

1

H

1.00797

This atomic mass is the one number that best represents the mass of all three versions of hydrogen.

1. First, you have to know the mass of each isotope

2. Second, you have to know the percent abundance*of each isotope

*see next slide

0

Calculating a “weighted” averagePercent abundance is how often that particular isotope occurs in a sample of the element

0

Percent abundance?A sample of magnesium collected anywhere in the universe will contain three isotopes of magnesium.

Sample of Magnesium

These are the percent abundances of each isotope of magnesium

0

Percent abundance?78.90% of this magnesium will be the isotope named “magnesium 24”

10.00% of this magnesium will be the isotope named “magnesium 25”

Sample of Magnesium

11.10% of this magnesium will be the isotope named “magnesium 26”

This data will be provided to you in problems or you will be given a table where you can look it up.

0

Percent abundance?78.90% of this magnesium will be the isotope named “magnesium 24”

10.00% of this magnesium will be the isotope named “magnesium 25”

Sample of Magnesium

11.10% of this magnesium will be the isotope named “magnesium 26”

(Mass of isotope #1)(percent abundance)

100

(Mass of isotope #2)(percent abundance)

100

(Mass of isotope #3)(percent abundance)

100

0

Calculating a “weighted” averageUsing the formula for calculating a weighted average

23.985045(.7890)

+24.985839(.1000)

+25.982595(.1110)

24.306852 amu’s

0

Calculating the Atomic mass of magnesiumSince its a “weighted”

average this number

has more influence since

this mass occurs 79% of

the time

It’s NOT just a straight

average where you add

the masses and divide

by 3

Note how the %

abundances were

converted to decimals

(just divide each by 100)

51.940510(0.8379)

+ 52.940651(0.0950)

53.938882(0.0236)

51.995926 amu’s

0

Calculate the atomic mass of chromiumAtomic number = the number of protons

- It’s the same as the element’s position on the periodic table
- For example, carbon is the 6th element on the table, so its atomic number is 6 which means it has 6 protons (and 6 electrons if it’s a neutral atom)

0

Vocabulary reviewAtomic mass = the “weighted” average mass of all the different isotopes of an atom

- This is the “weird” number on the periodic table that usually has a bunch of places past the decimal point

0

Vocabulary reviewMass number = the sum of protons + neutrons

- This one kind of makes sense because the electrons essentially don’t have any mass
- This HAS to be a whole number because you can’t have part of a proton or neutron
- Mass number is NOT given on the periodic table

0

Vocabulary reviewWhat is the mass number of a carbon atom that has 6 neutrons? 7 neutrons?

- How many neutrons does a nitrogen atom have if its mass number is 14?
- How many neutrons does a chlorine atom have if its mass number is 36?
- What is the atomic number of neon?
- What is the atomic mass of neon?

0

Let’s Practice Those Terms…0

A Short Way to Write Isotopes“A” is the symbol

for Mass Number

(#protons + #neutrons)

“Z” is the

symbol for

Atomic Number

(# of protons)

“X” will be the

symbol of the element

Jay - Z

Yo! If you’re doin’ chem problems I feel bad for you son….

I got 99 problems, and here’s the first one….HIT ME!!!!

Write aXz notation for an isotope that has 15 protons, 18 electrons, and 16 neutrons.

Problem #3Write aXz notation for an isotope that has 15 protons, 18 electrons, and 16 neutrons.

31P3-15

Problem #3This isotope is

also an ion!!!

How many protons, electrons, and neutrons are in this isotope?

41Ca2+ 20

20 protons, 18 electrons, 21 neutrons

Problem #4How many protons, electrons, and neutrons?

- 56Fe2+26 26, 24, 30
- 27Al3+13 13, 10, 14
- 79Se2-34 34, 36, 45

- Isotope with 21 protons, 18 electrons, and 24 neutrons
- Isotope with 53 protons, 74 neutrons, and 54 electrons

- Isotope with 21 protons, 18 electrons, and 24 neutrons

45Sc3+21

- Isotope with 53 protons, 74 neutrons, and 54 electrons

127I-53

More practice
Download Presentation

Connecting to Server..