Atoms – the Nucleus

Atom - review• smallest part of element (pure substance) that has

all the same properties of that element– For example, if you take a lump of coal (the

element carbon)– break it into smaller and smaller pieces, the

smallest piece that still acts like coal is one atom of carbon.

Parts of an Atom - Review

• 2 main parts–nucleus–electron cloud

• Empty Space!

Electron Cloud

Nucleus• Nucleus is the core of the atom

• Contains 2 subatomic particles:–Protons–Neutrons

+ Protons +• Charge = + (positive)

• Mass = 1 amu*atomic mass unit

• Location = nucleus

• Every atom of the same element has the same number of protons

• example:– All carbon atoms have 6 protons– All Hydrogen atoms have 1 proton

Sub-atomic particle

How do we know how many protons there are in a

single atom of an element? • Use your periodic table!

• The atomic number tells you how many protons there are!

A

How many protons are in 1 atom of:• Oxygen?• Nickel?• Hydrogen?

Which element has…

• 2 protons in it’s nucleus?• 11 protons in it’s nucleus?• 5 protons in it’s nucleus?

Pair Share…

• Do any two elements have the same number of protons? Why/why not?

= Neutrons =• Charge = 0 (neutral)

• mass = 1 amu- atomic mass unit

• Location = nucleus

Sub-atomic particle

How do we know how many neutrons there are in a single atom of an element?

• Use your periodic table!

First:With your partner determine the number of protons (atomic#) = _____

SECOND…Look at the atomic mass of your element

and round it to the nearest whole number = _____(This number shows you how many TOTAL subatomic particles should be in the nucleus of your atom. )

And last…

A

Protons (atomic#) + Neutrons = The atomic mass of an atom – all calculable mass is contained in the nucleus!

OR The atomic mass (rounded)– protons (atomic#) = the

number of neutrons!

How many neutrons does your element have? Raise your hand when you are ready for me to check your work!

Journal Questions – Write in complete sentences

1. Which 2 subatomic particles are found in the nucleus and what are their electrical charges?

2. Using an element key, how can you determine the number of protons an element has?

3. Using an element key, how can you determine the number of neutrons an element has?

4. What is special about the number of protons an atom has?

5. Where is all of the mass found in an atom?