Isotopes All atoms of an element have the same

number of protons.However, they can have a different number of neutrons. What do we call

an atom when they have the same # of protons, but a different # of neutrons?

ISOTOPESLets Explore Isotopes…

This nucleus is NOT an isotope because there are the same # of

protons & neutrons.

KEY:Green = ProtonsRed = Neutrons

ISOTOPE!There are a different # of protons &

neutrons. Let’s get a closer look…

They are still the same element. They are just a little different from every other atom of the same element.

If an atom has a MISSING neutron or an EXTRA neutron:ISOTOPE!

HYDROGEN

1 proton & 1 neutron = Hydrogen isotope1 proton & 2 neutrons = Hydrogen isotope

•Hydrogen has 1 proton. THIS WILL NEVER CHANGE! (If there are 2 protons, it isn’t hydrogen!)

•Most Hydrogen have no neutrons.

**The “1 proton” tells us it is hydrogen. Having neutrons tells us it is an isotope.**

Carbon

In nature, ALL carbon have 6 protons. Most carbon have 6 neutrons.

6 proton + 6 neutron

6 proton + 7 neutron

6 proton + 12 neutron

FIND THE ISOTOPE(S)…

Carbon

In nature, ALL carbon have 6 protons. Most carbon have 6 neutrons.

6 proton + 6 neutron

6 proton + 7 neutron

6 proton + 12 neutron

WHY ARE THEY ISOTOPES?

In nature, ALL carbon have 6 protons. Most carbon have 6 neutrons.

6 proton + 6 neutron

6 proton + 7 neutron

6 proton + 12 neutron

Because they have a different # of neutrons then what normally happens in nature.

How are we supposed to know what normally happens in

nature???Excellent question. Let’s go over how to read one

element box on the Periodic Table of Elements.

Element Name

Atomic Number (# of protons)

Element Symbol

Mass Number(sometimes called

Atomic Mass)

You know how to find the number of neutrons…

Subtract the # of protons from the Mass Number (rounded).

12 – 6 = 6 Neutrons

So, 6 protons & 6 neutrons are the

“normal” amounts of each found in nature.

Carbon:6 protons6 neutronsMass=12

CarbonISOTOPE:

6 protons8 neutronsMass=14

How do I know if it is a “regular” element or an isotope??

1. Use the Periodic Table of Elements as your baseline.

2. Calculate # neutrons for the element. (Mass – Protons = Neutrons)

3. Then look to see if your Element has more neutrons than the same element on the Periodic

Table.4. That’s it! If it has LESS or MORE neutrons –

ISOTOPE!

Carbon on the Periodic Table has a Mass Number of 12

and 6 protons.

Which one of these are ISOTOPES?

Carbon on the Periodic Table has a Mass Number

of 12 and 6 protons.12 – 6 = 6 Neutrons

ISOTOPES

13 – 6 = 7 Neutrons

14 – 6 = 8 Neutrons

This is a REALLY easy concept. If an element has more or less neutrons than

the same element on the periodic chart – ISOTOPE.

Questions? Ask Mrs. Cancel or another student

to help clarify.