biochemistry review

Question 1

What are living organisms composed of?

Answer 1

Matter.

Question 2

What is matter composed of?

Answer 2

Chemical elements

Question 3

How many elements are essential for human life?

Answer 3

About 25 elements are essential for human life

Question 4

What are compounds?

Answer 4

A compound is a substance consisting of two or more different elements in a fixed ratio.

Question 5

What do elements consist of?

Answer 5

Elements consist of unique atoms, which are made up of protons, neutrons, and electrons

Question 6

What are atoms made of?

Answer 6

Each atom is made up of three types of particles: Neutrons,Protons and Electrons orbiting the shells.

Question 7

What is atomic number?

Answer 7

The unique number of protons is an element’s atomic number.

Question 8

Atoms of the same element always have the same number of protons( atomic number), true or false?

Answer 8

True

Question 9

What are ions?

Answer 9

When an atom loses (+)or gains an electron(-), an ion is formed.

Question 10

What happens when the number of neutrons in an atom changes?

Answer 10

Atoms will have different masses, thus creating isotopes.

Question 11

How are chemical bonds formed?

Answer 11

An atom prefers to have a full amount of electrons in each shell (usually 2 or 8). If it doesn’t, it will interact with other atoms and share, gain, or lose electrons, resulting in attractions called chemical bonds

Question 12

Why are some elements very reactive?

Answer 12

The chemical properties of elements, like stabiltity depend on the number of electrons. Sodium for example wants to lose one electron, if it is unable to do so, it becomes extremely unstable and thus making it reactive.

Question 13

What is an ionic bond? Give an example.

Answer 13

Ionic bond: the transfer of an electron between atoms. Salt is an example ionic bond (sodium wants to lose an electron, chloride wants one , so they share)

Question 14

What is a covalent bond? Give an example.

Answer 14

Covalent bond: the sharing of electrons between atoms.

ex: O2, N2, H2O

Question 15

Covalent bonds are stronger than ionic bonds, true or false?

Answer 15

false. Ionic bonds are stronger than covalent bonds. Bond between H2, is covalent.

Question 16

What is a non polar molecule?

Answer 16

If a bond has a balanced charge, it is a nonpolar molecule. (carbon dioxide is non polar)

Question 17

What is a polar molecule?

Answer 17

If a bond has an unbalanced charge, it is a polar molecule.

Question 18

Why is water a polar molecule?

Answer 18

Water is polar as it consists of unbalanced charges. There are covalent bonds and hydrogen bonds.

Question 19

Why does water form hydrogen bonds?

Answer 19

Water is polar.

Question 20

Explain hydrogen bonds.

Answer 20

Hydrogen bonds are technically not considered ‘bonds’ since they are very weak. They are referred to as ‘‘electrostatic attractions’’.

Question 21

Why is water good as a dissolving agent and why is salt easily dissolved in water?

Answer 21

Water consists of electrostatic attractions, that will pull apart the chemical bonds of the solute, causing it to dissolve.

Salt is extremely polar because of chlorine pulling the electron very aggressively, and since water and salt is polar it dissolves easily. (like dissolves like)

Question 22

Why is water so versatile?

Answer 22

Water’s versatility as a solvent results from the polarity of its molecules

Question 23

How are aqueous solutions formed?

Answer 23

When polar or charged solute is dissolved in water molecules, it forms an aqueous solution.

Question 24

Non polar molecules are hydrophilic. True or false?

Answer 24

False. Non polar molecules are hydrophobic and polar molecules are hydrophilic.

Question 25

Differentiate a base and acid ?

Answer 25

Acid contains a large number of hydrogen ions. Base has either lost a large number of hydrogen ions or contains a large number of hydroxyl ions. (OH-)

Question 26

What is a buffer?

Answer 26

Buffer minimizes changes in ph.