Vocabulary

• ATOM-the smallest unit that maintains the characteristics of an element

– Nucleus- The center of the atom, contains protons and neutrons

– Electron Cloud –Region surrounding the nucleus containing the electrons

The Atom

The Atom

NucleusProtons

Neutrons

The NucleusProton-A positively charged sub-atomic particle

(+). Atomic Mass=1 amuThe number of protons is the same as the atomic

number

Li3

7 The atomic massThe atomic mass

The Atomic Symbol

The Nucleus

Neutrons –A sub-atomic particle in the nucleus--Has a mass equal to 1 atomic mass unit

--Neutron do not have a charge (0)To calculate the number of neutrons in an element…

Li3

7

The atomic number

The atomic massThe atomic mass

The atomic mass- The atomic number The number of neutrons

Li3

7

The atomic number

The atomic massThe atomic mass

7 (Atomic Mass)- 3 protons(Atomic #) 4 neutrons

WRITING RESPONSE

How many protons does Mg have?

How many neutrons does Mg Have?

WRITING RESPONSE

How many protons does Mg have?12

How many neutrons does Mg Have? 12

The Atom

The Electron Cloud

• Electrons-• The number of electrons equals the number of protons• Sub-atomic particle with a negative charge (-)• Electrons behave as if in a 3-D orbit

• Valence Electrons– The outer most electrons– Valence electrons are responsible for bonding

WRITING RESPONSE

How many protons?

How many neutrons?

How many electrons?

WRITING RESPONSE

How many protons? 3

How many neutrons? 4

How many electrons? 3

Bohr Model• The first shell can have

2 electrons• The second shell can

have 8 electrons

Shells and the Electron Cloud

Let’s look at a few elements…

Hydrogen 1= Proton 1= electron

Let’s look at a few elements…

Helium 2=protons 2=neutrons2=electrons

Let’s look at a few elements…

Lithium 3=protons 4=neutrons3=electrons

Let’s look at a few elements…

Fluorine9=protons 10=neutrons

9=electrons

Let’s look at a few elements…

Argon18=protons 22=neutrons

18=electrons

ISOTOPESAtoms that have the same # of protons but have neutrons that have been added, resulting in a different atomic mass.

IONSCharged particles that occur when an atom gains or loses an electron during chemical bonding.

• If the atom gains an electron- Negative charge• Ex: Cl-

• Most non-metals form negative Ions

• If the atom loses an electron- Positive Charge• Ex: Na+

• Most metals form Positive Ions

Losing an Electron = Positive ion Na+ has 11 protons but only 10 electrons

Gaining an Electron = Negative ion Cl- has 17 protons but has 18 electrons

What would the charge be on an atom that lost an electron? Gained two electrons?

Which shows a negative ion? Explain

Which shows a neutral atom? Explain

Which shows a positive atom? Explain

A

B

C