Atomic Structure Atomic Structure. Chemistry Joke Q: Where does a German chemist put his dirty dishes? A: In the Zn!

Atomic StructureAtomic Structure

Chemistry Joke

Q: Where does a German chemist put his dirty dishes?

A: In the Zn!

Modern ViewModern ViewThe atom is mostly The atom is mostly

empty space with 2 empty space with 2 regions:regions:

Nucleus with protons and neutrons

Electron cloud— region where you are most likely to find an electron

3 Subatomic Particles3 Subatomic ParticlesElectrons –

negative charge

Protons – positive charge

Neutrons – neutral (no charge)

-

-

- -

-+

+++

Protons and neutrons are made up of even smaller particles called quarks. VIDEO*

How Many Protons?How Many Protons?

Each atom has a unique number of protons that will Each atom has a unique number of protons that will NEVERNEVER change. change.

ATOMIC NUMBER: The number of protons in the ATOMIC NUMBER: The number of protons in the nucleus of an atomnucleus of an atom

Ex. Ex. AllAll atoms of oxygen have 8 protons, so the atomic atoms of oxygen have 8 protons, so the atomic number of oxygen is 8. number of oxygen is 8.

The atomic number (the number of protons) The atomic number (the number of protons) identifies the elementidentifies the element..

Atomic Number on the Periodic Atomic Number on the Periodic TableTable

1111

NaNa

Atomic Number

Symbol

11 Protons

How many protons does each atom have?How many protons does each atom have?

Nitrogen Nitrogen

Sulfur Sulfur

BariumBarium

7

16

56

How Many Electrons?How Many Electrons?

An atom is neutral. An atom is neutral.

If every element has positive protons in its If every element has positive protons in its nucleus then why don’t elements have a positive nucleus then why don’t elements have a positive charge?charge?

BecauseBecause…the number of electrons equals the …the number of electrons equals the number of protons in a neutral atom.number of protons in a neutral atom.

The charges cancel.The charges cancel.

The The net net charge is zero.charge is zero.

IonsIons

Atoms can gain or lose electrons. Atoms can gain or lose electrons.

When this happens, the atom becomes When this happens, the atom becomes charged and we call it an charged and we call it an IONION. .

If an atom loses electrons, it becomes If an atom loses electrons, it becomes positively charged.positively charged.

If an atom gains electrons, it becomes If an atom gains electrons, it becomes negatively charged.negatively charged.

How Many Neutrons?How Many Neutrons?

Atoms of the same element always have the same number of protons, but they can have different numbers of neutrons!

We call atoms of the same element that have a different # of neutrons ISOTOPESISOTOPES.

IsotopesIsotopes To identify isotopes, we have to use a To identify isotopes, we have to use a mass numbermass number.. The The MASS NUMBERMASS NUMBER is the total number of is the total number of pp+ + and n and noo

added together. added together. pp++ + n + noo = mass number = mass number Therefore…mass # ─ # p+ (atomic #) = # no

Ex. One carbon isotope has 7 neutrons. All carbon Ex. One carbon isotope has 7 neutrons. All carbon atoms have 6 protons, so its mass number is 13.atoms have 6 protons, so its mass number is 13.

Written as a name:

Carbon-13Or as a symbol:

13

6C

IsotopesIsotopes

The mass number is The mass number is NOTNOT given on the given on the periodic table!!!!periodic table!!!!

•The number on the periodic table is the ATOMIC MASSATOMIC MASS.

•That number is the weighted average mass of all of the isotopes of that element.

•Atomic Mass has decimal places.

•The Mass Number ( protons + neutrons) will always be a WHOLE Number.

Finding the # of NeutronsFinding the # of Neutrons

Ex. Beryllium-9 Ex. Beryllium-9 atomic # 4 atomic # 4 mass # 9mass # 9

# neutrons = 9 - 4 = 5 neutrons# neutrons = 9 - 4 = 5 neutronsHOW MANY PROTONS? ____ HOW MANY PROTONS? ____ ELECTRONS?___ELECTRONS?___

4

4

Subatomic Particles in Oxygen, Subatomic Particles in Oxygen, Phosphorus, & ZincPhosphorus, & Zinc

1616 3131 65 65

OO P P Zn Zn 88 1515 30 30

__ p__ p++ __ p__ p++ __ p __ p++

__ n__ n __ n__ n __ n __ n

__e__e-- __e__e-- __ e __ e--

Mass #

Atomic #

Chemistry Joke

Q: What do you do with a dead chemist?

A: Ba!