The Nature of Molecules and the Properties of Water

These flashcards review key concepts about the nature of molecules and the properties of water as discussed in the biology lecture notes.

What is the smallest unit of matter that retains the properties of an element?

Atom.

What are the three primary subatomic particles of an atom?

Protons, neutrons, and electrons.

What is the charge of protons?

Positive.

What is an ion?

A charged particle that has an imbalance of protons and electrons.

What is oxidation in terms of electron transfer?

The loss of an electron.

What is reduction in terms of electron transfer?

The gain of an electron.

What are valence electrons?

Electrons in the outermost energy level of an atom.

What is the octet rule?

Atoms tend to establish completely full outer energy levels.

Which four elements make up 96.3% of the human body weight?

Carbon, hydrogen, oxygen, nitrogen (CHON).

What is a compound?

A molecule containing more than one type of element.

How is an ionic bond formed?

Through the attraction of oppositely charged ions.

What results from the gain of an electron by a sodium atom?

The formation of a sodium ion (Na+).

What are covalent bonds?

Bonds formed when atoms share electrons.

What is electronegativity?

An atom's affinity for electrons.

What defines a polar covalent bond?

Unequal sharing of electrons.

What is the main property of water that allows it to form hydrogen bonds?

Polarity.

Why is solid water less dense than liquid water?

Because of the hydrogen bonds that hold water molecules at fixed distances.

What is meant by hydrophilic and hydrophobic?

Hydrophilic means 'water-loving' while hydrophobic means 'water-fearing'.

What is the pH scale?

A scale that measures the acidity or basicity of a solution.

What happens to water when it dissolves salt?

Water surrounds the sodium and chloride ions, forming hydration shells.

What makes a solution acidic?

A substance that increases the concentration of hydrogen ions when dissolved in water.

What is a buffer?

A substance that minimizes changes in pH.