Lecture 3

Question 1

What’s atomic mass?

Answer 1

protons + #neutrons

Question 2

Whats atomic number?

Answer 2

protons

Question 3

What’s an isotope?

Answer 3

It’s a version of an atom/element. This means there is the same number of protons but a different number of neutrons.

Question 4

What are stable isotopes?

Answer 4

Nuclei do not tend to lose particles.

Question 5

What are non stable/radioactive isotopes?

Answer 5

Nucleus gives off particles of energy as it decays spontaneously.

Question 6

Definition of ionizing radiation.

Answer 6

Its the particles of energy that are given off by non stable isotopes as the nucleus in the isotope decays.

Question 7

What kind of particles are emitted from non stable isotopes (ionizing radiation)?

Answer 7

X ray(s) or subatomic particles. Alpha or beta particles have energy to free electrons from atoms/molecules and ionize them.

Question 8

What is non-ionizing radiation?

Answer 8

It is any type of electromagnetic radiation that doesn’t have enough energy per quantum, therefore, it cannot ionize atoms or molecules.

Question 9

Give 3 examples of non-ionizing radiation.

Answer 9

1. Phones/mobiles
2. Radio-waves
3. Electropower transmission
   etc

Question 10

What are ions?

Answer 10

They are atoms/molecules that have a positive or negative charge. So #electrons CANNOT EQUAL #protons. So the net charge cannot equal to zero.

Question 11

What is a chemical bond?

Answer 11

It’s an attraction (bond) that holds two atoms together.

Question 12

Chemical bonds: What are covalent bonds?

Answer 12

Bond between the valence electrons of two atoms, where the valence electrons are shared.

Question 13

Chemical bonds: What are polar covalent bonds?

Answer 13

This is when the electrons are not shared equally between two atoms.

Question 14

What is electronegativity?

Answer 14

It’s how much an atom can attract electrons.

Question 15

Chemical bonds: What are hydrogen bonds?

Answer 15

It’s when a hydrogen atom is bounded to an electronegative atom and interacts with another atom of a different molecule that’s also electronegative.

Question 16

Chemical bonds: What are ionic bonds?

Answer 16

When two atoms pair together. One with low electronegativity and one with high electronegativity so that one atom can attract electrons easier than the other, which allows the high electronegativity atom to steal the valence electrons from the other atom.

Question 17

Chemical bond: What are van der Waals interactions?

Answer 17

They help stabilize molecules and influence the melting point of fatty acids. These happen when non-permanent positive and negative areas of molecules attract to each other. (They’re weaker than hydrogen bonds)

Question 18

What does it mean to be polar? And where does water stand in this?

Answer 18

Polar means that it allows the formation of h-bonds.

Question 19

What does it mean to be hydrophilic? Name 3 things

Answer 19

Love water, they’re polar and dissolve readily in water.

Question 20

What does it mean to be hydrophobic? Name 3 things

Answer 20

Fear water, they’re non-polar and don’t dissolve readily in water.

Question 21

How do H-bonds affect water molecules?

Answer 21

They cause them to stick together (become cohesive) and stick to other certain surfaces (become adhesive).It allows capillary action.

Question 22

What’s surface tension?

Answer 22

It’s a measure of how difficult it is to break the surface of a liquid.

Question 23

What’s specific heat?

Answer 23

It’s the amount of heat absorbed or lost to allow the change in temperature of 1 degree celsius.

Question 24

Explain the specific heat of water.

Answer 24

Water has a high heat capacity because of the H-bonds. When it’s heated, the H-bonds must be broken by the energy being absorbed. The energy, then increases the movement of the water particles. Water, thus resists temperature change.

Question 25

Solvent of life: Why does NaCl dissolve?

Answer 25

Due to the Na+ and Cl- ions becoming surrounded by water molecules.

Question 26

What do organic molecules contain?

Answer 26

Carbon. All living organisms are carbon-based. Our cells are formed by biomolecules that are made up of a carbon skeleton.

Question 27

Why is carbon so special?

Answer 27

1. Carbon atoms can form 4 covalent bonds. It can act as an intersection point where a molecule can branch off up to four directions.
2. Has the ability of each bond to rotate freely, which can create different shapes.

Question 28

What are isomers?

Answer 28

They’re molecules of different formations/structures but that have the same chemical formula.