DO NOW

• Draw a bohr model for Boron

DO NOW

• Describe what makes a source reliable and accurate?

HAPPY PT TUESDAY!!!!

ATOMIC NUMBER, ATOMIC MASS, AND ISOTOPES

BY THE END OF THE CLASS TODAY I WILL BE ABLE TO…

•Student will understand the symbol for an isotope

If we made a scale model of an atom and wanted to use Cowboy Stadium as our electron

cloud, the nucleus of the atom would be the size of the eraser on the end of your pencil. An

electron would still be smaller than the point on a straight pin.

WHAT DO THESE BOXES MEAN??

Number of protons/ Atomic Number

All atoms of the same element have the same

number of

protons

Number of Protons, Neutrons, & Electrons

- =

Mass Number

How to Use the Periodic Table

p+

e- n0

# Protons =

# Electrons =

# Neutrons =

Example 1: Argon

ISOTOPE SYMBOL

X: element symbol

ISOTOPE SYMBOL

A: Mass Number#protons + # neutrons in the nucleus

Always larger than Z

ISOTOPE SYMBOL

Z: Atomic number

#protons

2 WAYS TO WRITE ISOTOPE SYMBOL

Na11

23 Or Sodium-23

ISOTOPES OF SODIUM

Na11

Na11

23

24

EXAMPLE PROBLEM

•Write the nuclear notation for the chemical element that has 6 protons and 8 neutrons

#1•Write the Nuclear notation for the chemical element that has 17 protons and 16 neutrons (in your table)

Cl or Chlorine-3317

33

#2How many protons are in the isotope 54Cr? (Chromium-54) (add it to your table)

24 (like every atom of Chromium)

#3How many neutrons are in the isotope 42Ca? Number or protons? (add it to your table)

22 neutrons

#4How many electrons are in the isotope 23Na? Write it’s nuclear notation (add to table)

11 electrons

AVERAGE MASS OF SUBATOMIC PARTICLES

Subatomic Particle

Electric Charge

Mass Number (amu)

Location

Electron -1 0 Electron cloud

Proton +1 1 Nucleus

Neutron 0 1 Nucleus

Atomic Mass Unit 1 amu = 1.66 x 10-

24 g

EXAMPLE

+# p+ Mass of p+

x

Protons

# n0 Mass of n0

x

Neutrons

# e-Mass of e-

x

Electrons

+ = + + =

Example 7: Mass of Beryllium

4 Protons4 Electrons5 Neutrons

EXAMPLE 2 & 3

FluorineSodium

GALLERY WALK

• Walk around to the different pictures of isotopes• Identify which isotope it is and fill out the

information in your packet• Figure out – WHAT IS THE DIFFERENCE?

ISOTOPE

IsotopeNon-Examples

Definition

Drawing or Traits

Examples

ATOMS OF THE SAME ELEMENT WITH DIFFERENT NUMBERS OF NEUTRONS

(THEREFORE HAVE DIFFERENT MASSES).

Isotopes

COMPARE/CONTRAST

Differences from Basic Atom Similarities to Basic Atom

  

 

  

 

  

 

  

 

FOUR ISOTOPES OF HELIUM

1.What sub-atomic particle(s) are the same for the isotopes of Helium?

2.What sub-atomic particle(s) are different for the isotopes of Helium?

3.Are these four isotopes neutral? Why or Why not?

WORKOUT!

Write the following as an isotope symbol…

4. Copper-63 5. Copper-64 6. Lithium-7 7. Lithium-6

EXAMPLE PROBLEM

•How many neutrons are in the isotope of 26Mg?

Number of Neutrons = A-Z

#1How many neutrons are in the isotope 48Ti?

26 neutrons

EXAMPLE PROBLEM

How many electrons are in the isotope 23Na? (you can assume the atom is neutral)

11 electrons