Biochemistry

Question 1

A chemical substance that cannot be broken down further using standard chemical techniques is known as:

Answer 1

An element
For example, carbon (C) is an element. Atoms of a particular element always have the same number of protons. For example, all carbon atoms have 6 protons!

Question 2

What is the difference between an atom, a molecule, and a compound?

Answer 2

An atom is the fundamental unit of matter. Atoms contain protons, neutrons, and electrons.

A molecule is a group of two or more atoms, connected by chemical bonds (for example, O2).

A compound is a molecule that contains atoms of more than one element (for example, H2O).

Question 3

Which of the following are contained within the nucleus of a typical atom?

Protons
Neutrons
Electrons

Answer 3

A typical atomic nucleus contains protons and neutrons. Electrons are not found in the nucleus; instead, they are located in regions (“shells”) surrounding the nucleus.

Question 4

Isotopes are atoms with the same number of:

Answer 4

Protons

Isotopes are atoms with the same number of protons, meaning that they must represent the same element. Isotopes differ in their number of neutrons.

Question 5

an ionic bond

Answer 5

An ionic bond is a chemical bond that forms due to the complete transfer of electrons from one atom to another.

The atom that gains electrons is given a negative charge, while the atom that gives up electrons is given a positive charge.

Question 6

a covalent bond

Answer 6

A covalent bond is a chemical bond that forms via the sharing (not complete transfer) of electrons.

When the electrons are shared unequally, the bond is polar covalent. For example, H2O contains two polar covalent bonds between H and O, because these atoms have different electronegativities (attraction to electrons in a bond).

When the electrons are shared equally, the bond is nonpolar covalent. For example, O2 contains a nonpolar covalent bond between the two O atoms, which have the same electronegativity.