Question

protons, neutrons, and electrons practice worksheet
fill in the blanks in the following worksheet. please keep in mind that the isotope represented by each space may not be the most common isotope or the one closest in atomic mass to the value on the periodic table.

atomic symbol	atomic number	protons	neutrons	electrons	atomic mass
	11				24
		31	37
				39	89
	29		35
		43			100
pb					207
			102	70
		89			225
mo			53
	81				206
	100		159
no					261
yb					172
		106	159

Explanation:

Step1: Recall key atomic rules

1. Atomic number = number of protons = number of electrons (neutral atom)
2. Atomic mass = protons + neutrons
3. Atomic symbol matches atomic number (periodic table)

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Row 1 (Symbol B):

Step1: Find atomic number

Atomic number of B (boron) = 5, so protons = 5, electrons = 5

Step2: Calculate atomic mass

$\text{Atomic mass} = 5 + 6 = 11$

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Row 2 (Atomic number 11, mass 24):

Step1: Identify symbol & protons

Atomic number 11 = Na (sodium); protons=11, electrons=11

Step2: Calculate neutrons

$\text{Neutrons} = 24 - 11 = 13$

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Row 3 (Protons 31, neutrons 37):

Step1: Identify symbol & atomic number

Protons=31 = Ga (gallium); atomic number=31, electrons=31

Step2: Calculate atomic mass

$\text{Atomic mass} = 31 + 37 = 68$

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Row 4 (Electrons 39, mass 89):

Step1: Find protons & atomic number

Electrons=39 = protons=39 = Y (yttrium); atomic number=39

Step2: Calculate neutrons

$\text{Neutrons} = 89 - 39 = 50$

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Row 5 (Atomic number 29, neutrons 35):

Step1: Identify symbol & protons

Atomic number 29 = Cu (copper); protons=29, electrons=29

Step2: Calculate atomic mass

$\text{Atomic mass} = 29 + 35 = 64$

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Row 6 (Protons 43, mass 100):

Step1: Identify symbol & atomic number

Protons=43 = Tc (technetium); atomic number=43, electrons=43

Step2: Calculate neutrons

$\text{Neutrons} = 100 - 43 = 57$

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Row 7 (Symbol Pb, mass 207):

Step1: Find atomic number

Atomic number of Pb (lead) = 82; protons=82, electrons=82

Step2: Calculate neutrons

$\text{Neutrons} = 207 - 82 = 125$

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Row 8 (Neutrons 102, electrons 70):

Step1: Find protons & atomic number

Electrons=70 = protons=70 = Yb (ytterbium); atomic number=70

Step2: Calculate atomic mass

$\text{Atomic mass} = 70 + 102 = 172$

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Row 9 (Protons 89, mass 225):

Step1: Identify symbol & atomic number

Protons=89 = Ac (actinium); atomic number=89, electrons=89

Step2: Calculate neutrons

$\text{Neutrons} = 225 - 89 = 136$

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Row 10 (Symbol Mo, neutrons 53):

Step1: Find atomic number

Atomic number of Mo (molybdenum) = 42; protons=42, electrons=42

Step2: Calculate atomic mass

$\text{Atomic mass} = 42 + 53 = 95$

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Row 11 (Atomic number 81, mass 206):

Step1: Identify symbol & protons

Atomic number 81 = Tl (thallium); protons=81, electrons=81

Step2: Calculate neutrons

$\text{Neutrons} = 206 - 81 = 125$

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Row 12 (Atomic number 100, neutrons 159):

Step1: Identify symbol & protons

Atomic number 100 = Fm (fermium); protons=100, electrons=100

Step2: Calculate atomic mass

$\text{Atomic mass} = 100 + 159 = 259$

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Row 13 (Symbol No, mass 261):

Step1: Find atomic number

Atomic number of No (nobelium) = 102; protons=102, electrons=102

Step2: Calculate neutrons

$\text{Neutrons} = 261 - 102 = 159$

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Row 14 (Symbol Yb, mass 172):

Step1: Find atomic number

Atomic number of Yb (ytterbium) = 70; protons=70, electrons=70

Step2: Calculate neutrons

$\text{Neutrons} = 172 - 70 = 102$

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Row 15 (Protons 106, neutrons 159):

Step1: Identify symbol & atomic number

Protons=106 = Sg (seaborgium); atomic number=106, electrons=106

Step2: Calculate atomic mass

$\text{Atomic mass} = 106 + 159 = 265$

Answer:

Atomic symbol	Atomic number	Protons	Neutrons	Electrons	Atomic mass
Na	11	11	13	11	24
Ga	31	31	37	31	68
Y	39	39	50	39	89
Cu	29	29	35	29	64
Tc	43	43	57	43	100
Pb	82	82	125	82	207
Yb	70	70	102	70	172
Ac	89	89	136	89	225
Mo	42	42	53	42	95
Tl	81	81	125	81	206
Fm	100	100	159	100	259
No	102	102	159	102	261
Yb	70	70	102	70	172
Sg	106	106	159	106	265