AP Biology: Covalent, Ionic Bonds, and Molecular Structure

List the four most prevalent elements for life in order from most to least electronegative.

Oxygen > Nitrogen > Carbon > Hydrogen

What is a covalent bond?

A covalent bond is formed by the sharing of electrons between atoms.

What distinguishes a nonpolar covalent bond from a polar covalent bond?

Nonpolar covalent bonds involve equal sharing of electrons due to similar electronegativities, while polar covalent bonds involve unequal sharing due to differing electronegativities.

What happens to shared electrons in a covalent bond when electronegativities are equal?

Each electron rotates around each atom for the same amount of time.

What occurs to shared electrons in a covalent bond when electronegativities are unequal?

Electrons spend more time around the atom with higher electronegativity.

How does a hydrogen bond occur?

A hydrogen bond occurs when a slightly positive hydrogen atom is attracted to a slightly negative atom in a separate molecule, typically after forming a polar covalent bond.

Why is molecular shape crucial in biology?

Molecular shape determines how molecules interact with each other, affecting their biological functions.

Compare the shapes of water and carbon dioxide and their implications.

Water has a bent shape, creating polarity and allowing it to act as a solvent, while carbon dioxide has a linear shape, making it nonpolar.

How does an ionic bond occur?

An ionic bond occurs after the transfer of electrons, creating a pair of oppositely charged ions: a cation (positive) and an anion (negative).

What is the importance of bond strength in biological systems?

Bond strength dictates a molecule's stability; strong bonds provide structural integrity, while weak bonds offer flexibility for dynamic biological processes.

Rank the strength of ionic, covalent, and hydrogen bonds.

Covalent bonds are the strongest, followed by ionic bonds, then hydrogen bonds.

What is electronegativity?

Electronegativity is the pull an atom has on shared electrons in a chemical bond.

How can you determine the number of protons, neutrons, and electrons in an atom?

Using the atomic number and mass of an element, you can calculate the number of protons (equal to atomic number), neutrons (mass - protons), and electrons (equal to protons in a neutral atom).

What does a structural formula represent in terms of bonds?

A single line represents a single bond, two lines represent a double bond, and three lines represent a triple bond.

What is the bonding capacity of an atom with 4 valence electrons?

The bonding capacity is 4.

How many valence electrons does an atom with an atomic number of 6 have?

It has 4 valence electrons.

What is the significance of valence electrons in bonding?

Valence electrons determine how many bonds an atom can form with other atoms.