Atoms

ATOMS

Atom Smallest part of an

element with all the properties of that element.

2 parts

1. Nucleus Center of

atom most of

atomic mass contains

protons & neutrons

Nucleus

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Mass Number Mass # = Mass of

the nucleus 1 proton = 1amu

(atomic mass unit) 1 neutron = 1 amu The average #

protons + # neutrons

Electrons too small to contribute to mass

What is the mass (rounded to the nearest whole number) of an atom of each of these elements?

11

NaSodium22.99

24

CrChromium

51.99

36

KrKrypton83.80

Na = 23 Cr = 52 Kr = 84

A. 11B. 23C. 22.99D. 22

A. 24B. 51C. 51.99D. 52

A. 36B. 83C. 83.80D. 84

2. Electron Cloud Cloud of electrons

that surrounds the nucleus

Individual electrons move so fast, they appear as a cloud

Most of the volume of the atom.

Mostly empty space. -

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Electron Cloud

3 subatomic particles1. Protons: positive charge

(+) located in nucleus2. Neutrons: neutral charge (=)

located in nucleus

3. Electrons: negative charge (-)located in the

electron cloud

Protons # protons (positive charges) = atomic # Atoms of different elements have

different numbers of protons.

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Atomic Numbe

r

How many protons (+) are in the nucleus of an atom of each of these elements?

11

NaSodium22.99

24

CrChromium

51.99

36

KrKrypton83.80

Na = 11+

Cr = 24+

Kr = 36+

A. 36B. 83C. 83.80D. 84

A. 24B. 51C. 51.99D. 52

A. 11B. 23C. 22.99D. 22

Different elements have different numbers of protons (+). Which atom has 8 protons? Which atom has 6 protons? Which atom has 7 protons?

A. Carbon B. NitrogenC. Oxygen D. Moccium

6

CCarbon12.01

7

NNitrogen14.00

8

OOxygen15.99

OxygenCarbonNitrogen

Neutrons # neutrons (neutral, no charge)

=mass – protons (atomic #)

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Atomic Number

(# protons)

Mass (# protons + # neutrons

11 (rounded) -5 6 neutrons

How many neutrons (=) are in the nucleus of an atom of each of these elements?

11

NaSodium22.99

24

CrChromium

51.99

36

KrKrypton83.80

Na23-11

12 =

Cr52-24

28 =

Kr84-36

48 =

A. 11B. 12C. 22.99D. 22

A. 24B. 26C. 28D. 52

A. 36B. 48C. 83.80D. 84

Electrons # electrons (negative) = # protons

(atomic #) # negative charges = # positive

charges, the atom is neutrally charged (has no charge)

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Atomic Numbe

r

How many electrons (-) are in the electron cloud of an atom of each of these elements?

11

NaSodium22.99

24

CrChromium

51.99

36

KrKrypton83.80

Na = 11-

Cr = 24- Kr = 36-A. 36B. 83C. 83.80D. 84

A. 24B. 51C. 51.99D. 52

A. 11B. 23C. 22.99D. 22

13

AlAluminum

26.98

1. How many protons (+) does an atom of Aluminum have?

2. How many electrons (-) does an atom of Aluminum have?

3. How many neutrons (=) does an atom of Aluminum have?

27 (mass #)-13 (atomic #) 14 =

13 -

13 +A. 13 B. 14C. 26 D. 27

A. 13 B. 14C. 26 D. 27

A. 13 B. 14C. 26 D. 27

12

MgMagnesium

24.31

1. How many protons (+) does an atom of Magnesium have?

2. How many electrons (-) does an atom of Magnesium have?

3. How many neutrons (=) does an atom of Magnesium have?

24 (mass #)-12 (atomic #) 12 =

12 -

12 +A. 12 B. 13C. 24 D. 25

A. 12 B. 13C. 24 D. 25

A. 12 B. 13C. 24 D. 25

15

PPhosphorus

30.97

1. How many protons (+) does an atom of Phosphorus have?

2. How many electrons (-) does an atom of Phosphorus have?

3. How many neutrons (=) does an atom of Phosphorus have?

31 (mass #)-15 (atomic #) 16 =

15 -

15 +A. 15 B. 16C. 30 D. 31

A. 15 B. 16C. 30 D. 31

A. 15 B. 16C. 30 D. 31

Fill in the table below.

Element Atomic # Mass # Protons+

Neutrons=

Electrons-

Boron 5 11

Neon 20 10

Fluorine 9 10

5 5 6

10 10 10

9 19 9

How many protons (+), neutrons (=), and electrons (-) does an atom of Boron have?

A. 5 (+), 5(=), 5(-) B. 11(+), 11(=), 11(-)

C. 5 (+), 6(=), 5(-) D. 5(+), 11(=), 5(-)

What is the atomic # of Neon, and how many protons (+) and neutrons (=) does an atom of it have?

A. At#10, 20(+), 10(=) B. At#10, 10(+), 10(=)

C. At#20, 10(+), 10(=) D. At#10, 10(+), 20(=)

What is the atomic # and mass of Fluorine, and how many electrons (-) does an atom of it have?

A. At#10, mass 19, 10(-) B. At#19, mass 9, 9(-)

C. At#9, mass 10, 9(-) D. At#9, mass 19, 9(-)

Energy Levels # shells = # of ROW on Periodic Table

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2nd Row

2 Energy Levels

Where do the Electrons go? 1st Shell = No more than 2 2nd Shell = No more than 8 3rd Shell = No more than 8 Last Shell = # of COLUMN on Periodic

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5 Electrons

2 Electrons in 1st shell

B is in 3rd Column

3 electrons in last shell

Diagram Atoms 1 -18 Teacher demonstrates diagramming

atoms with atomic #1, #2, #3, #10, #18 Students work with partners – one sheet

of paper per team. Take turns diagramming the atoms.

While one draws, the other checks work. One person diagrams the odd numbered

elements, partner checks work. The other person diagrams the even

numbered elements, partner checks work.