How are atoms studied?

• Atoms are the building blocks of matter

• Atoms are too small in size to study easily

• Size of Earth : soda can = soda can : atom

Who studied the atom?

• Studied by many scientists for centuries– Democritus (400 BC) – phrase “atomos”– Rutherford (1911) – nucleus (gold foil expt)– Moseley (1913) – X-rays to find atomic #– *Bohr (1913) – planetary model of the atom– *Schrödinger (1923) – electron cloud model

I’m an electron!

I’m a proton!I’m a neutron!

I was walking along and I saw these two.

I was telling jokes to the neutron.The proton and I were having fun.

They looked so happy there together.

I was p o s i t i v e l y charged!I couldn’t have amassed more happiness.

The proton looked happy, so I wandered closer.

I could see the electron coming near.The who? Huh?

They were HUGE next to me!

The electron was so cute!Like a speck of dust, or something…

I didn’t want to seem obvious, so I kept walking.

Around and around the electron goes.Hey electron, you’re making the proton dizzy.

The proton seems so happy with the neutron.

I’m having fun, but I still notice the electron.It won’t bother me if the electron hangs around.

I guess I’ll just wander around out here.

I’m happy hanging out here.The center is cool, but sometimes it can be a “Bohr”.

Electrons circle around the nucleus of an atom.

Protons are a main part of the nucleus of an atom.Neutrons also hang out in the nucleus of an atom.

Electrons have a negative charge. Protons have a positive charge. +Neutrons have no charge. 0

Electrons are little and have a mass of almost zero.

Protons are big and have a mass of one.Neutrons are also big and have a mass of one.

What is the structure of an atom?• Nucleus – center of the atom

– Home of Protons and Neutrons

– Proton• Has a positive (+) charge

• Has a relative mass of 1

• Determines the atomic number

• Found inside the nucleus

What is the structure of an atom?

– Neutron• Has no (0) charge

• Has a relative mass of 1

• Determines the isotope– Isotopes are two of the same

element with different masses

• Found inside the nucleus

What is the structure of an atom?• Electron

– Has a negative (-) charge

– Has a relative mass of 0 (zero)

– Determines the ion

– Found outside the nucleus• Bohr model – electrons are in specific

energy levels• Electron cloud model – electrons are in a

random cloud

What is the structure of an atom?

Bohr Model

“Planetary Model”

Schrödinger Model

“Electron Cloud Model”

How are P, N, e- related?

• # protons = atomic number

• # electrons = # protons in a neutral atom

• # protons + # neutrons = atomic mass

What is a chemical symbol?

• Chemical symbol tells us what atom it is

• Always a CAPITAL LETTER, sometimes followed by a lower case letter

• Ex: Oxygen O Nitrogen N Sodium Na

• *Cobalt – Co *Carbon Monoxide – CO

• (Co is an element, CO is a compound)