Worksheet on the composition of matter, including definitions and multiple-choice questions.

Let's solve the "Composition of Matter" review worksheet step by step. I'll go through each section and provide correct answers with explanations.

---

VOCABULARY REVIEW: Define the following terms

1. Atom
→ The smallest unit of an element that retains the chemical properties of that element. It consists of a nucleus (protons and neutrons) surrounded by electrons.

2. Electron
→ A negatively charged subatomic particle that orbits the nucleus in energy levels or shells. Electrons are involved in chemical bonding.

3. Compound
→ A substance formed when two or more different elements are chemically bonded together in a fixed ratio. For example, water (H₂O) is a compound of hydrogen and oxygen.

4. Covalent bond
→ A type of chemical bond where two atoms share one or more pairs of electrons. This typically occurs between nonmetals.

5. Ion
→ An atom or molecule that has gained or lost one or more electrons, giving it a net positive or negative charge. Positively charged ions are called cations; negatively charged ones are anions.

---

MULTIPLE CHOICE: Write the correct letter in the blank

1. The atomic number of carbon is 6. Therefore, the number of protons in a carbon atom equals:
→ c. 6
✔ Explanation: The atomic number = number of protons. Carbon has atomic number 6 → 6 protons.

2. One of the kinds of particles found in the nucleus of an atom is:
→ d. proton
✔ Explanation: The nucleus contains protons (positively charged) and neutrons (neutral). Electrons are outside the nucleus.

3. The maximum number of electrons that can be held in an atom’s second energy level is:
→ b. 8
✔ Explanation: The second energy level (n=2) can hold up to 8 electrons (2 in the s subshell, 6 in the p subshell).

4. Of the following elements, the one that is most likely to form ionic bonds is:
→ b. sodium
✔ Explanation: Sodium (Na) is a metal (alkali metal), which readily loses an electron to form a positive ion. Metals tend to form ionic bonds with nonmetals. Hydrogen, carbon, and oxygen are nonmetals and usually form covalent bonds.

5. An example of a compound is:
→ a. water
✔ Explanation: Water (H₂O) is made of hydrogen and oxygen chemically bonded in a fixed ratio.
- Hydrogen gas (H₂) and oxygen gas (O₂) are elements, not compounds.
- Chloride ion (Cl⁻) is an ion, not a compound.

---

✔ Final Answers:

Vocabulary Review:
1. Atom – Smallest unit of an element retaining its chemical properties.
2. Electron – Negatively charged particle orbiting the nucleus.
3. Compound – Substance formed by chemically combining two or more elements.
4. Covalent bond – Shared pair(s) of electrons between atoms.
5. Ion – Charged particle due to loss or gain of electrons.

Multiple Choice:
1. c
2. d
3. b
4. b
5. a

Let me know if you'd like this formatted for printing or need help with other sections!