Chemistry and Biochemistry 1 Flashcards
(79 cards)
Define chemistry
the science that deals with the composition and properties of substances and various elementary forms of matter
Define Biochemistry
The science concerning the chemical and physicochemical processes and substances that occur within living organisms.
What is matter?
Matter is everything around us that occupies space
What are atoms?
Atoms are small particles that make up matter - the lego bricks that make up everything in our universe.
They’re made up of electrons, protons and neutrons.
What is an element? Give 3 examples
An element is a substance made up of just one type of atom so it cannot be split up into simpler substances.
EG:
Hydrogen
Carbon
Calcium
Magnesium
What are the 4 main elements that are present in the human body? And what percentages do they occupy?
Oxygen - 65%
Carbon - 18%
Hydrogen - 10%
Nitrogen - 3%
(Other elements making up the remaining 4%)
Is there any relation between elements that sit next to each other in the periodic table?
Yes - elements close to each other will be similar in size and reactivity and so can interfere with each others absorption.
EG Floride and Chloride can interfere with Iodine
What are subatomic particles?
The building blocks of an atom - protons, neutrons and electrons.
Compare how are protons, neutrons and electrons positioned, weighted, and charged.
Protons and neutrons are in the centre of the atom whereas electrons move around the outside.
Protons are positively charged and weigh 1 unit
Neutrons have no charge and weigh 1 unit
Electrons are negatively charged and weigh 0 units
Describe the electron shell including the numbers associated with them.
The electron shell describes the rings around that centre of the atom that the electrons move around.
Within the shell, electrons like to be paired up and for the outer shell to be full. They become reactive if this isn’t the case - becoming a free radical.
Inner shell = 2 electrons
Then 8 electrons
Then 8 electrons
Then 18 electrons
Explain what the atomic number, and atomic weight/mass refers to in the periodic table.
Atomic number = how many protons and electrons (each) there are
Atomic mass = total weight so therefore includes the neutrons. NB round decimals up/down
EG
Atomic number = 19
Atomic mass - 39
= 19 protons & 19 electrons
= 20 neutrons (39-19)
What does the elements in column 1 of the periodic table all react with?
Water
NB The lower down in the column, the more reactive.
Name 3 elements that you find within the halogens
Floride
Chloride
Iodine
What are isotopes? And give 1 example.
Atoms of the same element that have a different number of neutrons in the nucleus.
This therefore doesn’t affect their charge, but does affect their mass.
EG Most carbon has a mass of 12, but some weigh 14.
How do isotopes play a role in radioactivity?
Some isotopes have such an imbalance of protons and neutrons in the nucleus that it causes the atom to become unstable and radioactive.
EG radiotherapy uses gamma rays from radioactive isotopes
Describe Hydrogen in relation to its subatomic particles and behaviour.
Hydrogen contains just 1 proton, 1 electron and 0 neutrons.
As the electron isn’t paired, the atom wants to find another atom that is missing an electron so it can give it away.
By giving it away, the hydrogen particle becomes positively charged (H+)
What is meant by an inert element?
Inert elements have a full outer shell and so do not easily react.
What’s the difference between an ionic bond and covalent bond?
Ionic = atoms transfer electrons from 1 to the other.
Covalent bonds = atoms share electrons.
Why does ionic bonding create a bond?
Once an electron has been transferred from one atom to another, they become positively and negatively charged. This difference in charge causes an attraction/bond.
What’s an ion? And give 1 example
It refers to atoms that have either gained or donated an electron therefore becoming either positively or negatively charged.
For, Ca2+ has given away 2 electrons, becoming positively charged.
Does sodium tend to come positively or negatively charged?
Positively charged.
It has only 1 electron on its outer shell, so it’s easier to give one away than try to gain 7. So it becomes Na+
Give an example of a covalent bond
Water - H2O
2 Hydrogens join the oxygen to share the electrons. This means that:
The 2 hydrogen gain an electron each to make up the full 2 electrons of their only shell/
Oxygen gains 2 electrons to complete its 8 electrons in its outer shell.
What are polar covalent bonds?
When electrons are shared unequally due to some atoms having more “pulling power” than others.
Explain 1 of the most important examples of a polar bond.
Oxygen and hydrogen:
Oxygen pulls electrons towards itself resulting in negatively charged areas over the oxygen and positively charged areas over each hydrogen.
The positive hydrogens on one atom attract the negatively charged oxygen of another. These attractions give water properties such as surface tension and the ability to dissolve so many different things.