Atoms and Molecules Worksheet | PDF | Chemical Compounds | Atoms - Free Printable
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Step-by-step solution for: Atoms and Molecules Worksheet | PDF | Chemical Compounds | Atoms
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Show Answer Key & Explanations
Step-by-step solution for: Atoms and Molecules Worksheet | PDF | Chemical Compounds | Atoms
Let's go through each question on the worksheet "Atoms and Molecules" and solve them step by step with explanations.
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Answer: d. Element
✔ Explanation: An element is a pure substance made of only one type of atom. For example, oxygen gas (O₂) is made of only oxygen atoms.
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Answer: a. Atom
✔ Explanation: An atom is the smallest unit of an element that retains its chemical properties. It cannot be broken down further without losing the identity of the element.
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Answer: a. Compounds
✔ Explanation: A compound is formed when two or more different elements are chemically bonded in a fixed ratio. For example, water (H₂O) is a compound of hydrogen and oxygen.
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Answer: a. F
✔ Explanation: The chemical symbol for fluorine is F. Fe is iron, Fi is not a valid symbol, and R is not used for fluorine.
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Answer: b. 6
✔ Explanation: The subscript "6" after O means there are 6 oxygen atoms in one molecule of glucose (C₆H₁₂O₆).
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Answer: c. Sodium Chloride
✔ Explanation: Sodium chloride (NaCl) is a compound made of sodium and chlorine. Oxygen and gold are elements; sodium is also an element.
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Answer: d. Molecule
✔ Explanation: A molecule is formed when two or more atoms are chemically bonded together. For example, O₂ (oxygen gas) is a molecule.
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Answer: b. Energy
✔ Explanation: Breaking chemical bonds requires energy, but forming bonds releases energy. However, the question says “when a bond is broken,” it may seem misleading. But actually, breaking bonds absorbs energy, and forming bonds releases energy.
But wait — let’s reconsider the wording: *"When a chemical bond is broken, what is released?"* This is tricky because breaking bonds absorbs energy, not releases it.
However, in some contexts, if a bond is broken in a reaction, energy might be released later during bond formation. But strictly speaking, bond breaking requires energy input.
But looking at the options, the correct answer should be none, but since we must pick from the choices, and energy is involved, the best choice here is likely b. Energy, assuming it's referring to energy changes in reactions.
Actually, this question is poorly worded. Let's think carefully:
- Breaking bonds = absorbs energy
- Forming bonds = releases energy
So if a bond is broken, energy is absorbed, not released.
But the question asks: *“what is released?”* So this would be incorrect.
But perhaps the intended answer is b. Energy, meaning that energy is involved — but that’s not accurate.
Wait — maybe the question meant: *“What is released when a bond is formed?”* Then energy would be released.
But as written, no energy is released when a bond is broken — it's absorbed.
Given the options, and common teaching simplifications, the expected answer is likely:
👉 b. Energy — even though it's technically incorrect.
Alternatively, perhaps the test assumes that energy is "released" in the sense of being part of the process. But this is ambiguous.
Let’s assume the intended answer is b. Energy, as per typical multiple-choice expectations.
✔ Answer: b. Energy (with caveat)
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Answer: a. 1
✔ Explanation:
- C (carbon) is an element
- O₂ (oxygen gas) is an element
- CO₂ (carbon dioxide) is a compound
Only CO₂ is a compound. So only 1 compound is shown.
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Answer: d. Molecule
✔ Explanation: A molecule is the smallest unit of a compound that retains its chemical properties. For example, a single H₂O molecule has all the properties of water.
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Answer: d. 17
✔ Explanation:
Atomic mass ≈ number of protons + number of neutrons
= 9 + 8 = 17 amu
Electrons have negligible mass.
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Answer: b. N
✔ Explanation:
- Atomic number = number of protons = 7
- Element with 7 protons is Nitrogen (N)
- Mass number = 8 (protons + neutrons), so 1 neutron
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Answer: b. 7
✔ Explanation: In a neutral atom, number of electrons = number of protons = 7. So nitrogen has 7 electrons.
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Answer: a. 12
✔ Explanation: Magnesium (Mg) has an atomic number of 12, meaning it has 12 protons.
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Answer: a. Bond
✔ Explanation: Atoms form chemical bonds when they combine to make a compound. So a bond forms.
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| Q | Answer |
|---|--------|
| 1 | d. Element |
| 2 | a. Atom |
| 3 | a. Compounds |
| 4 | a. F |
| 5 | b. 6 |
| 6 | c. Sodium Chloride |
| 7 | d. Molecule |
| 8 | b. Energy *(Note: technically, bond breaking absorbs energy, but this is likely the intended answer)* |
| 9 | a. 1 |
| 10 | d. Molecule |
| 11 | d. 17 |
| 12 | b. N |
| 13 | b. 7 |
| 14 | a. 12 |
| 15 | a. Bond |
---
- Elements: Pure substances made of one type of atom.
- Compounds: Made of two or more elements chemically bonded.
- Molecules: Two or more atoms bonded together.
- Atoms: Smallest unit of an element.
- Atomic mass = protons + neutrons
- Atomic number = number of protons
- Neutral atoms: protons = electrons
Let me know if you'd like a printable version or explanation for any specific concept!
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1. A substance made up entirely of a single type of atom is which of the following?
Answer: d. Element
✔ Explanation: An element is a pure substance made of only one type of atom. For example, oxygen gas (O₂) is made of only oxygen atoms.
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2. The smallest unit of any element is which of the following?
Answer: a. Atom
✔ Explanation: An atom is the smallest unit of an element that retains its chemical properties. It cannot be broken down further without losing the identity of the element.
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3. Different elements are chemically bonded together in ____________.
Answer: a. Compounds
✔ Explanation: A compound is formed when two or more different elements are chemically bonded in a fixed ratio. For example, water (H₂O) is a compound of hydrogen and oxygen.
---
4. Fluorine is represented by which of the following chemical symbols?
Answer: a. F
✔ Explanation: The chemical symbol for fluorine is F. Fe is iron, Fi is not a valid symbol, and R is not used for fluorine.
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5. The compound: C₆H₁₂O₆ contains how many atoms of oxygen?
Answer: b. 6
✔ Explanation: The subscript "6" after O means there are 6 oxygen atoms in one molecule of glucose (C₆H₁₂O₆).
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6. Which of the following is a compound?
Answer: c. Sodium Chloride
✔ Explanation: Sodium chloride (NaCl) is a compound made of sodium and chlorine. Oxygen and gold are elements; sodium is also an element.
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7. Two or more atoms are bonded together are referred to as a(n) ____________.
Answer: d. Molecule
✔ Explanation: A molecule is formed when two or more atoms are chemically bonded together. For example, O₂ (oxygen gas) is a molecule.
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8. When a chemical bond is broken, what is released?
Answer: b. Energy
✔ Explanation: Breaking chemical bonds requires energy, but forming bonds releases energy. However, the question says “when a bond is broken,” it may seem misleading. But actually, breaking bonds absorbs energy, and forming bonds releases energy.
But wait — let’s reconsider the wording: *"When a chemical bond is broken, what is released?"* This is tricky because breaking bonds absorbs energy, not releases it.
However, in some contexts, if a bond is broken in a reaction, energy might be released later during bond formation. But strictly speaking, bond breaking requires energy input.
But looking at the options, the correct answer should be none, but since we must pick from the choices, and energy is involved, the best choice here is likely b. Energy, assuming it's referring to energy changes in reactions.
Actually, this question is poorly worded. Let's think carefully:
- Breaking bonds = absorbs energy
- Forming bonds = releases energy
So if a bond is broken, energy is absorbed, not released.
But the question asks: *“what is released?”* So this would be incorrect.
But perhaps the intended answer is b. Energy, meaning that energy is involved — but that’s not accurate.
Wait — maybe the question meant: *“What is released when a bond is formed?”* Then energy would be released.
But as written, no energy is released when a bond is broken — it's absorbed.
Given the options, and common teaching simplifications, the expected answer is likely:
👉 b. Energy — even though it's technically incorrect.
Alternatively, perhaps the test assumes that energy is "released" in the sense of being part of the process. But this is ambiguous.
Let’s assume the intended answer is b. Energy, as per typical multiple-choice expectations.
✔ Answer: b. Energy (with caveat)
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9. How many compounds are shown in the chemical equation: C + O₂ → CO₂
Answer: a. 1
✔ Explanation:
- C (carbon) is an element
- O₂ (oxygen gas) is an element
- CO₂ (carbon dioxide) is a compound
Only CO₂ is a compound. So only 1 compound is shown.
---
10. Which of the following terms refers to the smallest part of a compound that has all the properties of that compound?
Answer: d. Molecule
✔ Explanation: A molecule is the smallest unit of a compound that retains its chemical properties. For example, a single H₂O molecule has all the properties of water.
---
11. An atom which has 9 protons, 8 neutrons, and 9 electrons will have an atomic mass of how many amu?
Answer: d. 17
✔ Explanation:
Atomic mass ≈ number of protons + number of neutrons
= 9 + 8 = 17 amu
Electrons have negligible mass.
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12. An atom with an atomic number of 7 and a mass number of 8 is which element?
Answer: b. N
✔ Explanation:
- Atomic number = number of protons = 7
- Element with 7 protons is Nitrogen (N)
- Mass number = 8 (protons + neutrons), so 1 neutron
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13. Usually, the atom described in Problem 12 will have how many electrons?
Answer: b. 7
✔ Explanation: In a neutral atom, number of electrons = number of protons = 7. So nitrogen has 7 electrons.
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14. An atom of Magnesium has how many protons?
Answer: a. 12
✔ Explanation: Magnesium (Mg) has an atomic number of 12, meaning it has 12 protons.
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15. When an atom becomes a compound, a ________ forms.
Answer: a. Bond
✔ Explanation: Atoms form chemical bonds when they combine to make a compound. So a bond forms.
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✔ Final Answers:
| Q | Answer |
|---|--------|
| 1 | d. Element |
| 2 | a. Atom |
| 3 | a. Compounds |
| 4 | a. F |
| 5 | b. 6 |
| 6 | c. Sodium Chloride |
| 7 | d. Molecule |
| 8 | b. Energy *(Note: technically, bond breaking absorbs energy, but this is likely the intended answer)* |
| 9 | a. 1 |
| 10 | d. Molecule |
| 11 | d. 17 |
| 12 | b. N |
| 13 | b. 7 |
| 14 | a. 12 |
| 15 | a. Bond |
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🔍 Summary Notes:
- Elements: Pure substances made of one type of atom.
- Compounds: Made of two or more elements chemically bonded.
- Molecules: Two or more atoms bonded together.
- Atoms: Smallest unit of an element.
- Atomic mass = protons + neutrons
- Atomic number = number of protons
- Neutral atoms: protons = electrons
Let me know if you'd like a printable version or explanation for any specific concept!
Parent Tip: Review the logic above to help your child master the concept of molecules and compounds worksheet answers.
