Atoms Worksheet Middle School Beautiful atomic Structure Worksheet ... - Free Printable

Let's solve this step by step based on the information provided in the image.

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Understanding the Periodic Table Square:

Each square represents an element with key atomic information:

- Top left number: Atomic Number (number of protons)
- Symbol: Element symbol
- Name: Element name
- Bottom number: Atomic Mass (average mass of atoms, including protons and neutrons)

Also:
- Atomic number = number of protons
- Atomic mass ≈ number of protons + number of neutrons (rounded to nearest whole number)
- In neutral atoms: # of electrons = # of protons

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Fill in the blanks for each element:

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#### 1. Oxygen (O)

Given:
- Atomic Number = 8
- Symbol = O
- Name = Oxygen
- Atomic Mass = 15.999

So:
- Atomic # = 8
- Atomic Mass = 15.999
- # of Protons = 8
- # of Neutrons = Atomic Mass (rounded) – Protons = 16 – 8 = 8
- # of Electrons = 8 (neutral atom)

> Note: We round 15.999 → 16 for neutron calculation.

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#### 2. Zinc (Zn)

Given:
- Atomic Number = 30
- Symbol = Zn
- Name = Zinc
- Atomic Mass = 65.39

So:
- Atomic # = 30
- Atomic Mass = 65.39
- # of Protons = 30
- # of Neutrons = 65 (rounded) – 30 = 35
- # of Electrons = 30

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#### 3. Lithium (Li)

Given:
- Atomic Number = 3
- Symbol = Li
- Name = Lithium
- Atomic Mass = 6.941

So:
- Atomic # = 3
- Atomic Mass = 6.941
- # of Protons = 3
- # of Neutrons = 7 (rounded from 6.941) – 3 = 4
- # of Electrons = 3

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#### 4. Silicon (Si)

Given:
- Atomic Number = 14
- Symbol = Si
- Name = Silicon
- Atomic Mass = 28.086

So:
- Atomic # = 14
- Atomic Mass = 28.086
- # of Protons = 14
- # of Neutrons = 28 (rounded) – 14 = 14
- # of Electrons = 14

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#### 5. Boron (B)

Given:
- Atomic Number = 5
- Symbol = B
- Name = Boron
- Atomic Mass = 10.81

So:
- Atomic # = 5
- Atomic Mass = 10.81
- # of Protons = 5
- # of Neutrons = 11 (rounded from 10.81) – 5 = 6
- # of Electrons = 5

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#### 6. Bromine (Br)

Given:
- Atomic Number = 35
- Symbol = Br
- Name = Bromine
- Atomic Mass = 79.904

So:
- Atomic # = 35
- Atomic Mass = 79.904
- # of Protons = 35
- # of Neutrons = 80 (rounded) – 35 = 45
- # of Electrons = 35

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Now, fill in the blanks at the top:

> Atomic number equals the number of ________ or ________
→ protons or electrons (in a neutral atom)

> Atomic mass equals the number of ________ + ________
→ protons + neutrons

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✔ Final Answer Summary:

#### Oxygen (O):
- Atomic #: 8
- Atomic Mass: 15.999
- Protons: 8
- Neutrons: 8
- Electrons: 8

#### Zinc (Zn):
- Atomic #: 30
- Atomic Mass: 65.39
- Protons: 30
- Neutrons: 35
- Electrons: 30

#### Lithium (Li):
- Atomic #: 3
- Atomic Mass: 6.941
- Protons: 3
- Neutrons: 4
- Electrons: 3

#### Silicon (Si):
- Atomic #: 14
- Atomic Mass: 28.086
- Protons: 14
- Neutrons: 14
- Electrons: 14

#### Boron (B):
- Atomic #: 5
- Atomic Mass: 10.81
- Protons: 5
- Neutrons: 6
- Electrons: 5

#### Bromine (Br):
- Atomic #: 35
- Atomic Mass: 79.904
- Protons: 35
- Neutrons: 45
- Electrons: 35

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✔ Fill-in-the-blank Answers:

> Atomic number equals the number of
> → protons or electrons

> Atomic mass equals the number of
> → protons + neutrons

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