Chemistry and biochemistry Flashcards
(73 cards)
Definition of chemistry
The science that deals with the composition and properties of substances and various elementary forms of matter (gas, liquid, solid)
Definition of biochemistry
The science concerned with the chemical and physicochemical processes and substances that occur within living organisms
Definition of matter
Everything around us that has mass and occupies space. Atoms make up matter. Atoms are made up of electrons, protons and neutrons.
Definition of an element
Substance made up of just one type of atom - cannot be split into a simpler substance. Elements we know of are in the periodic table.
How many different elements are normally present in the human body?
26
What are the four major elements which account for 96% of the human body?
Oxygen (65%), carbon (18%), hydrogen(10%) and nitrogen (3%).
What is an isotope?
Different versions of the same element due to a different number of neutrons in the nucleus. Does not affect chemical activity, but does change the mass.
Example of an isotope?
Carbon 12 - 6 protons, 6 neutrons
Carbon 14 - 6 protons, 8 neutrons
What causes radioactivity?
Radioactive isotopes - an imbalance of protons and neutrons in the nucleus - too many neutrons, means the element is unstable and will attempt to lose energy in the form of radioactivity.
What diagnostic techniques use radioactive isotopes?
PET Scan
Radiotherapy - radioactive tracers emit gamma rays to target rapidly dividing cells. Also highly damaging to healthy tissues.
Breath test for H. pylori
What is ionic bonding?
One atom gives an electron to another atom creating positive and negative charged ions that are attracted to each other.
What is covalent bonding?
Atoms share electrons.
Explain what is meant by an ‘ion’?
A charged atom that has either gained or lost an electron.
What is the ionisation?
The process of giving up or gaining electrons
What does it mean when an atom has a positive charge?
The atom has given up electrons and so has more protons than electrons eg Ca2+ has donated two electrons.
What does it mean when an atom has a negative charge?
The atom has gained electrons, so it has more electrons than protons.
What is a covalent bond?
When two elements share electrons - they both have the ‘magic number’ they are looking for. Eg H2O
What is a polar bond?
Where electrons are shared unequally. This happens because some atoms have a lot of ‘electron pulling power’.
Why is water known as the ‘universal solvent’?
Unique ability to dissolve anything with polar bonds or ionic compounds and therefore can dissolve more substances than any other liquid. This means wherever water goes it takes along valuable chemicals, minerals and nutrients, such as salt.
What is an electrolyte?
An ionic compound (eg salt) dissolved in water.
What are the seven key electrolytes in the body?
Sodium, potassium, chloride, calcium, magnesium, phosphate and bicarbonate.
Why are electrolytes important?
- conduct electricity, so essential for nerve and muscle function
- water balance as they exert osmotic pressure
- acid-base balance
What is an acid?
A substance that releases a high amount of H+ ions when dissolved in water.
What is a base?
A substance which binds to H+ ions in solution, creating lots of OH-.