Biology: Periodic Table, Chemical Bonds, Water Properties, Radioactive Decay, pH

What are the four main elements that make up the human body?

Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) - collectively known as CHON.

What does the equation F=ma represent?

It represents Newton's second law of motion, where F is force, m is mass, and a is acceleration.

What is radioactive decay?

It is the process by which unstable isotopes break down into particles with lower atomic numbers.

What are some uses of radioactive isotopes?

They are used for dating fossils and in medical procedures.

What characterizes short-lived isotopes?

They decay rapidly and do not harm the body, making them useful as tracers in medical diagnoses.

What is a molecule?

A molecule is a group of atoms held together by energy in the form of a covalent chemical bond.

What are the three principal types of chemical bonds?

Ionic bonds, covalent bonds, and hydrogen bonds.

What is an ionic bond?

An ionic bond is formed by the attraction between oppositely charged ions.

What is a covalent bond?

A covalent bond is formed when two atoms share electrons.

What are Van der Waals forces?

They are weak chemical attractions that occur when atoms are very close to each other.

What are unique properties of water?

Heat storage, ice formation, high heat of vaporization, cohesion, and adhesion.

Why does water have a high heat of vaporization?

Because it requires a significant amount of energy to break hydrogen bonds during vaporization.

What is cohesion in relation to water molecules?

Cohesion is when one water molecule is attracted to another water molecule.

What is adhesion in relation to water molecules?

Adhesion is when polar molecules other than water stick to a water molecule.

What is a polar molecule?

A polar molecule has a slight positive charge on one side and a slight negative charge on the other due to unequal sharing of electrons.

What happens when water ionizes?

It can spontaneously break into a positively charged hydrogen ion (H+) and a negatively charged hydroxide ion (OH-).

How is pH measured?

pH is measured as pH = -log[H+], representing the concentration of hydrogen ions in a solution.

What does a change of 1 unit on the pH scale represent?

It represents a tenfold change in hydrogen ion concentration.

What is the pH of pure water?

The pH of pure water is 7, indicating neutrality.

What is the significance of hydrogen bonding in water?

Hydrogen bonding confers many special properties to water, such as its high specific heat and solvent capabilities.