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MassachusettsChemistry

Module 2: Bonding and molecular structure

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do you write the formula of a compound from its ions, and how do you name ionic and covalent compounds?

Write chemical formulas by balancing ionic charges (including polyatomic ions), and name ionic and simple covalent compounds using the standard rules (MA STE HS-PS1-2 support, formulas and naming).
A standard-level answer on chemical nomenclature for Massachusetts high school chemistry: writing ionic formulas by balancing charge, using polyatomic ions, naming ionic compounds and those with multivalent metals, and naming covalent compounds with prefixes.
11 min answer →

How do the forces between particles determine bulk properties such as melting point, boiling point, and solubility?

Compare the strengths of intermolecular forces (dispersion, dipole-dipole, hydrogen bonding) and the bonds in ionic and network solids, and use them to explain bulk properties (MA STE HS-PS1-3, structure and forces between particles).
A standard-level answer on intermolecular forces for Massachusetts high school chemistry: dispersion, dipole-dipole, and hydrogen bonding compared with the strong bonds in ionic and covalent network solids, and how these forces set melting point, boiling point, and solubility, grounded in HS-PS1-3.
12 min answer →

Why do atoms bond, and how do ionic and covalent bonds form from the behavior of valence electrons?

Explain how ionic bonds form by transfer of electrons and covalent bonds by sharing, predict which forms from the elements involved, and relate bond type to properties (MA STE HS-PS1-2, bonding from electron states).
A standard-level answer on ionic and covalent bonding for Massachusetts high school chemistry: how electron transfer makes ions and ionic bonds, how sharing makes covalent bonds, predicting bond type from metal versus nonmetal, and the resulting properties, grounded in HS-PS1-2.
12 min answer →

How does metallic bonding explain the properties of metals, and why does the molecular-level structure of a designed material set its function?

Explain metallic bonding as a lattice of cations in a sea of delocalised electrons, relate it to the properties of metals, and connect molecular-level structure to the function of designed materials (MA STE HS-PS2-6(MA)).
A standard-level answer on metallic bonding and materials for Massachusetts high school chemistry: the sea-of-electrons model, why metals conduct, bend, and shine, alloys, and how the molecular structure of designed materials such as polymers and ceramics sets their function, grounded in HS-PS2-6(MA).
11 min answer →

How does a molecule's shape arise from its electron pairs, and what makes a molecule polar or nonpolar?

Predict molecular shape from electron-pair repulsion, use electronegativity difference to identify polar bonds, and decide whether a molecule is polar or nonpolar from its shape (MA STE HS-PS1-3 support, structure and polarity).
A standard-level answer on molecular shape and polarity for Massachusetts high school chemistry: electron-pair repulsion and common shapes, electronegativity difference and bond polarity, and how shape decides whether a whole molecule is polar, supporting HS-PS1-3.
12 min answer →