Structure of Atoms and Molecules - Covalent Bonding Practice

Practice flashcards covering covalent bonding, valence electrons, CH4 and hydrocarbons, ball-and-stick models, covalent naming, and polyatomic ions as described in the notes.

What is the key structural difference between molecular (covalent) compounds and ionic compounds?

Molecular compounds are true molecules formed by covalent bonds between two or more nonmetals; ionic compounds form crystal lattices of alternating positive and negative ions and do not consist of discrete molecular units (e.g., NaCl).

Which elements participate in molecular (covalent) compounds?

Only nonmetals; metals are not involved in molecular compounds.

What bonding strategy do molecular compounds use?

Covalent bonding by sharing valence electrons to achieve a full octet.

How is the valence electron count for atoms determined in this course?

Count up to 8 valence electrons; noble gases have 8; the first column elements have 1; transition metals are ignored for this class.

What are the valence electron counts for hydrogen and helium?

Hydrogen and helium can hold only 2 electrons in their valence shells.

How is H2 formed according to electron sharing?

Two H atoms share their valence electrons so each has a filled 2-electron valence shell; the shared electrons are shown as a bond.

How many hydrogen atoms are needed for carbon to complete its octet in CH4?

Four hydrogen atoms (C forms four covalent bonds with H).

What is CH4, and why is it called methane?

Methane; the principal component of natural gas; formed by covalent bonds between carbon and hydrogen.

What are hydrocarbons?

Hydrocarbons are covalent compounds composed only of carbon and hydrogen, such as CH4 and propane (C3H8).

How many carbon and hydrogen atoms are in propane?

Propane has the formula C3H8: three carbons and eight hydrogens.

What is octane and why is the name 'octane' used?

C8H18; octane has eight carbon atoms and is a component of gasoline.

What is a ball-and-stick model used for in chemistry?

A visual representation with balls as atoms and sticks as bonds to show the 3D structure and bond angles.

In common oxygen bonding scenarios, how many bonds and lone pairs does oxygen have in water?

Oxygen typically forms two bonds and has two lone pairs (octet; some valence electrons are not used in bonding).

What is the typical bond angle around carbon in CH4 as shown in ball-and-stick models?

Approximately 109.5 degrees (tetrahedral geometry).

How are covalent compounds named?

Name the first element, name the second element with an -ide ending, and use Latin prefixes (mono, di, tri, tetra, penta, hex, hepta, octa, nona, deca) to indicate numbers.

What is the name for CO2?

Carbon dioxide.

What is a common name for H2O?

Water (not dihydrogen monoxide).

What are polyatomic ions and how do they bond?

Polyatomic ions are groups of covalently bonded atoms that carry an overall ionic charge and participate in ionic bonding as a unit.

Describe the bonding inside the sulfate ion, SO4^2−.

Sulfate has covalent S–O bonds: two S–O single bonds and two S=O double bonds; the 2− charge is concentrated on the singly bonded O atoms; a 3D arrangement is shown by wedges.

What is Na2SO4 and how are its bonds characterized?

Sodium sulfate is an ionic compound with a crystal lattice of Na+ and SO4^2−; within the sulfate ion, bonds are covalent; thus compounds with polyatomic ions involve both ionic and covalent bonds.