Atomic Composition

– Atomic Structure

Write down three things you know about the atom.

ELECTRON e-

Negatively Charged

Atomic Mass – 0.0005 amu

Basically round to zero amu

3 Major Subatomic Particles

PROTON p+

Positive Charge

Mass of 1.007 amu

Found in nucleus of atom

Neutron no

No charge - “neutral”

Mass of 1.0009 amu

Found in Nucleus

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Symbol -ZAll atoms of

the same element have

the same number of protons in

the nucleus.

Atomic Number

ATOMIC NUMBER = NUMBER OF PROTONS

Symbol -AMass comes from the nucleus of the atom.

Mass number = # protons + # neutrons

Mass Number

No overall Charge

Number of protons and electrons are

the same

Neutral Atom -0r- Ground State

Ion

There was either:

1. Gain of electron(s)

2. Loss of electron(s)

What if it is not neutral?

X+

X-

Metals vs. NonmetalsMETALS LOSE ELECTRONS BECOMING POSITIVELY CHARGED.

NONMETALS GAIN ELECTRONS BECOMING NEGATIVELY CHARGED.

Example Using the Bohr Model

Na is a metal and wants to lose an electron so it has a full energy level of electrons.

Cl is a nonmetal and wants to gain and electron so it can have a full energy level.

1s22s22p6

3s1

1s22s22p63s2

3p5

Example Using the Bohr Model

11 protons and 10 electrons make an ion with a +1 charge.

17 protons and 18 electrons make an ion with a -1 charge.

1s22s22p6 1s22s22p63s2

3p6

How do we write all of this information?

Complete Chemical Symbol

Write the symbol for the atom with 28 protons, 28 electrons and 31 neutrons.

Ni1. Look up the symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number.

2. Write the number of protons in the lower left hand side of the element.

28

3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass.

59

4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge.

How do we write all of this information?

Complete Chemical Symbol

Write the symbol for the ion with 8 protons, 10 electrons and 8 neutrons.

O1. Look up the symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number.

2. Write the number of protons in the lower left hand side of the element.

8

3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass.

16

4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge.

-2

How do we write all of this information?

Complete Chemical Symbol

Write the symbol for the ion with 20 protons, 18 electrons and 20 neutrons.

Ca 1. Look up the

symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number.

2. Write the number of protons in the lower left hand side of the element.

20

3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass.

40

4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge.

+2

How do we write all of this information?

Element name – atomic mass

How many protons, neutrons and electrons are in Tantalum-181.

1. The number of protons comes from the atomic number.

2. The number of electrons equals the number protons because this is a neutral atom.

Protons – 73 Electrons – 73 Neutrons – 108

3. The number of neutrons is equal to the mass number minus the atomic number.