Lecture 3: Biochemistry I

Question 1

Definition of Chemistry

Answer 1

the science that deals with the composition and properties of substances and various
elementary forms of matter (gas, liquid, solid).

Question 2

Definition of Biochemistry

Answer 2

the science concerned with
the chemical and physicochemical processes
& substances that occur within living organisms.

Question 3

What is Matter?

Answer 3

is everything around us that has mass and occupies space.

Question 4

What’s atoms?

Answer 4

Atoms are small particles that make up matter - the “Lego bricks” that make up everything in our universe.
Atoms are made up of electrons, protons & neutrons.

Question 5

What is an element?

Answer 5

An element is a substance made up of just one type of atom so it cannot be split up into simpler substances.

Question 6

How many elements in the human body?

Answer 6

26 different elements are normally present in the human body.

Question 7

4 major elements in the human body?

Answer 7

carbon, hydrogen, oxygen and nitrogen, which account for 96% of the human body

Question 8

What atoms are made of?

Answer 8

Each atom is made up of subatomic particles called protons, neutrons and electrons.

Question 9

Name the THREE subatomic particles and give their weight and charge.

Answer 9

Protons have a positive charge and a mass of approximately 1 atomic unit.
Neutrons have no charge and a mass of approximately 1 atomic unit.
Electrons are negatively charged particles
that ‘buzz’ around the outside of the nucleus,
creating an electron cloud. They have virtually no mass at all.

Question 10

What properties of an atom make it react chemically?

Answer 10

All the chemical properties of an atom are down to its number of protons and electrons. The neutrons just add weight to the atom; they don’t significantly change how it chemically reacts.

Question 11

What determines where each element is on the periodic table?

Answer 11

Elements are arranged in columns and rows that show which elements share similar reactivity and physical properties.

Question 12

What is the atomic number?

Answer 12

The number that is assigned to each

element tells us how many protons and, therefore, how many electrons each atom has.

Question 13

What is the large number on on each element of the period table?

Answer 13

The larger number is always the mass number (the weight in atomic units). It tells us how much the atom weighs so it can be used to work out the number of neutrons (remembering that electrons weigh nothing).

Question 14

Column 7 - The Halogens?

Answer 14

Fluorine, Chlorine, Bromine, Iodine, Astatine.

Question 15

Describe the association between Iodine and Fluorine.

Answer 15

They both in the same group in the periodic table - they are both in group 7 so they have similar chemical reactivity but fluorine is much more powerful than iodine. Fluorine in excess on our daily lives can force iodine out of the way and it can compromise thyroid function.

Question 16

Explain what is meant by an ‘ion’?

Answer 16

It’s a charged atom- An Ion is an atom that gives or receives an electron.

Question 17

Give the chemical symbol for Potassium.

Answer 17

K

Question 18

Name the THREE subatomic particles and give their weight and charge.

Answer 18

Protons which has a positive charge and weighs 1/ Neutrons which has a neutral charge and weighs 1/ Electrons which has a negative charge and weighs 0

Question 19

Explain what is meant by an ‘isotope’. Give ONE example.

Answer 19

The same element that has a different atomic mass. Ie. Carbon 12 and Carbon 14

Question 20

How many electrons are required to fill the second electron shell?

Answer 20

8 electrons to fill the second shell

Question 21

Describe what happens in ionic bonding.

Answer 21

This is where 1 atom gives an electron to another atom creating a positive and a negative charged ions that are attracted to each other.

Question 22

Name the FOUR most electronegative elements.

Answer 22

Fluorine, Chlorine, Oxygen and Nitrogen

Question 23

Give an example of a polar molecule.

Answer 23

The most common is water

Question 24

Explain what is meant by the ‘universal solvent’.

Answer 24

It is water unique ability to dissolve anything with polar bonds or with ionic compound- things with positive and negative charge.

Question 25

Atomic number

Answer 25

number of protons

Question 26

Mass number

Answer 26

number of protons + number of neutrons.

Question 27

Number of neutrons

Answer 27

Mass number (always bigger) – atomic number

Question 28

How Isotopes are used in medicine? Give an example.

Answer 28

Some diagnostic techniques in medicine use radioactive tracers which emit gamma rays from within the body. ie. Radiotherapy and H. pylori test

Question 29

What makes chemical reactions on an atom?

Answer 29

Electrons always want to be in pairs. All of the reactions that happen in Chemistry are driven by atoms trying to end up with a stable and full outer shell either by stealing, giving away (donating) or sharing electrons.

Question 30

What is the simplest atom of all and why?

Answer 30

Hydrogens is the simplest atom because it only contains one proton and one electron and no neutron.

Question 31

What is bonding in chemistry?

Answer 31

Atoms that are trying to become stable by bonding with other atoms so that they can get just the right number of electrons in their outer shell.

Question 32

What are the 2 main types of bonding?

Answer 32

Ionic bonding – atoms transfer electrons (1 donates, 1 receives).
Covalent bonding – occurs when atoms share electrons.

Question 33

What is an ionic bonding?

Answer 33

Ionic bonds occur when one atom donates some of its electrons to another.

Question 34

What is an Ion?

Answer 34

If an atom gives up or gains electrons to fill its outer shell, it becomes an ion.

Question 35

What is covalent bonds?

Answer 35

occur when two elements share electrons so that they both have the “magic number” they are looking fo

Question 36

What is Polar bonds?

Answer 36

Polar covalent bonds form where electrons are shared unequally.

Question 37

What is electronegative elements?

Answer 37

Some elements have lots of protons compared to the number of electron shells i.e. a strong positive centre. These elements are referred to as ‘electronegative’ because they tend to pull the shared electrons towards themselves.

Question 38

What’s a Hydrogen Bonding?

Answer 38

One of the most important examples of a polar bond are the bonds between Oxygen and Hydrogen in water.
• The oxygen pulls the electrons towards itself, resulting in a negatively charged area over the oxygen and
a positively charged area over each hydrogen.