Question

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Explanation:

The problem is about chemical bonding, which falls under the subfield of Chemistry in Natural Science. To answer these questions, we recall basic chemical bonding concepts:

1. An atom is most stable when its valence shell (outer energy level) is filled. For most atoms, this is 8 electrons (octet rule, except for some like H with 2).
2. Properties of compounds are different from the elements that form them (e.g., H₂O vs H₂ and O₂).
3. a. Chemical formula: Uses symbols to represent the ratio of atoms in a compound (e.g., H₂O).

b. Subscript: In a chemical formula, a small number below and to the right of an element symbol showing the number of atoms of that element (e.g., 2 in H₂O).
c. Chemical bond: The force that holds atoms together in a compound, formed by electron sharing or transfer.

1. Atoms become stable by gaining, losing, or sharing valence electrons.
2. Losing electrons (losing negative charge) makes a positive ion (cation).
3. Gaining electrons (gaining negative charge) makes a negative ion (anion).
4. A positive ion (cation) has more protons than electrons (since it lost electrons, protons > electrons).
5. A negative ion (anion) has more electrons than protons (since it gained electrons, electrons > protons).
6. Groups 1, 2, and 13 (alkali metals, alkaline earth metals, and some metalloids) lose electrons to form cations (they have 1, 2, or 3 valence electrons, easier to lose than gain).
7. Groups 15, 16, 17 (pnictogens, chalcogens, halogens) gain electrons to form anions (they need 3, 2, or 1 more electron to fill the valence shell, easier to gain than lose).

Answer:

1. valence shell; 8
2. different
3. a. A chemical formula uses element symbols and subscripts to represent the ratio of atoms in a compound.

b. A subscript in a chemical formula is a small number below and to the right of an element symbol, indicating the number of atoms of that element.
c. A chemical bond is the force that holds atoms together in a compound, formed by electron transfer (ionic) or sharing (covalent).

1. gain; lose; share
2. positive
3. negative
4. protons; electrons
5. electrons; protons
6. Groups 1, 2, and 13 (or 1A, 2A, 3A)
7. Groups 15, 16, 17 (or 5A, 6A, 7A)