Atoms and Molecules Flashcards
define what it is meant by the key term ‘atom’
atoms are units of matter that form all chemical substances. each type of atom (eg - oxygen, nitrogen) is known as a ‘chemical element’
state the 4 components of atoms
- atoms are made of protons, neutrons and electrons
- protons and neutrons are found in the atomic nucleus
- electrons are found orbiting the atomic nucleus in orbitals
- an atom is most stable when the outer orbital has a pair of electrons
what percentage of atoms in the body are made from Hydrogen, Oxygen, Carbon and Nitrogen
- Hydrogen - 63%
- Oxygen - 26%
- Carbon - 9%
- Nitrogen 1%
what percentage of atoms in the body is made up from mineral elements
0.7% total atoms in the body
what percentage of atoms in the body is made up from trace elements
less than 0.01% total atoms in the body
define what it is meant by the key term ‘atomic number’
the atomic number is the total number of protons that an atom has
state 2 facts about the atomic number
- different atoms have different amounts of protons so the atomic number helps us distinguish between elements
- as atoms are electrically neutral, the atomic number also tells us how many electrons the atom has
define what it is meant by the key term ‘atomic mass’
atomic mass indicates an atoms mass in relation to other atoms based upon carbon having an atomic mass of 12
define what it is meant by the key term ‘Dalton’
a Dalton (d) is the unit used to measure atomic mass. one dalton is equal to 1/12 the mass of a carbon atom
define what it is meant by the key term ‘isotope’
an isotope is a different version of the same atom where the total number of neutrons in the atom has changed
state 2 facts about isotopes and radiation
- isotopes are unstable so can randomly release energy or even components of the isotope itself
- this is known as radiation and such isotopes are known as ‘radioisotopes’
state 2 benefits of radioisotopes
- the special qualities of radioisotopes are of great practical use in medicine (eg - killing cancer cells)
- radioisotopes can also be useful is medical diagnosis
state what it is meant by the key term ‘gram atomic mass’
- the gram atomic mass of a chemical element is the amount of the element, in grams, equal to the numerical value of it’s atomic mass
- eg - 12g of carbon (assuming it’s all C12) is 1g atomic mass of carbon
define what it is meant by the key term ‘ion’
- an ion is an atom which has gained, or lost, one or more electron(s)
- the result is a full orbital in the atoms valence shell meaning it has become chemically stable
define what anions and cations are
- anions are ions created where atoms have gained electrons and has become negatively charged
- cations are ions created where atoms have lose electrons and has become positively charged
state 3 facts about ions
- because of their charge, ions can conduct energy when dissolved in water
- the ionic forms of mineral elements are often referred to as electrolytes
- electrolytes are used to carry electrical charges across cell membranes so serve as an electrical current in certain cells
state 4 facts about the anatomic composition of the body
- H, O, C and N account for 99% of the atoms in the body
- the 7 essential mineral elements are the most abundant substances dissolved in the ejxtracelleur and intracelleur fluids
- most of body’s calcium and phosphorus make the solid matrix of bone tissue
- the 13 essential trace elements are required for normal body growth and function
state what it is meant by the key term ‘molecules’
molecules are formed when two or more atoms bond together
define what it is meant by the key term ‘compound’
a compound is where two or more molecules bond together
state what it is meant by a ‘covalent bond’
a covalent bond is where two or more atoms with partially filled valance shells bind together by sharing electrons to fill their valance shells
state 3 facts about covalent bonds
- covalent bonds make atoms chemically stable
- covalent bonds are the strongest chemical bond between atoms
- covalent bonds can usually only be broken via heat or enzyme action
define the key term ‘electronegativity’
electronegativity is the measure of an atoms ability to attract electrons in a covalent bond
what factors effect electronegativity
- the more positively charged an atoms atomic nucleus is the greater the atoms electronegativity
- electronegativity decreases the greater the distance between the atoms valance shell and atomic nucleus increases
define what it is meant by the key term ‘polar-covalent bonds’
polar covalent bonds occur when two, or more, atoms bond and the electrons will spend more time orbiting the atom with a greater electronegativity creating a polarity across the covalent bond
state 3 facts about polar molecules
- polar bonds do not have a net electrical charge as the overall charge of the molecule is stable
- polar molecules tend to be more soluble in water than non-polar molecules
- polar molecules readily dissolve in blood, interstitial fluid and intracelleur fluid
define what it is meant by the key term ‘non-polar covalent bonds’
non-polar covalent bonds is where a covalent bond is formed between two, or more, atoms of the same electronegativity
what are non-polar molecules
non polar molecules are molecules that contain a large proportion of non-polar covalent bonds
state 2 facts about non-polar molecules
- electrons are, or nearly, evenly shared between atoms in the covalent bond so no unequal charge is formed
- when in fluid, they usually associate with polar molecules as a ‘carrier’ to prevent the non-polar molecules from coming out of the solution
state what it is meant by the key term ‘ionic bond’
an ionic bond is formed via chemical attraction between opposingly charged atoms
define what it is meant by the key term ‘hydrogen bond’ (H-bond)
- H-bonds are formed when two polar molecules in close proximity of each other form an electrical attraction between them
- such bonds may also form on an intra-anatomical Lebel
state 3 facts about H-bonds
- represented by dashed lines in diagrams
- although weak individually, when in large numbers, they play a key role in deterring the shape of large molecules
- essential in physiology as shape effects function (eg - enzymes)
define what it is meant by the key term ‘ionization’
ionisation is the process of forming ions. this process can happen either, on atoms individually, or atoms covalently linked in a molecule
what are the two groups of atoms that usually undergo ionisation
- the Carboxyl group (COOH) - ionises when the O2 linked to H captures the H’s electron releasing a proton
- the amine group (NH2) - binds to the H+ released by the carboxyl group
define what it is meant by the key term ‘free radicals’
free radicals are atoms with an unpaired electron in an orbital of their valance shell
state 3 facts about free radicles
- atoms are most stable with paired electrons outer orbital
- free radicles are unstable and can react with other atoms in the process of oxidation
how can free radicles be treated in the body
antioxidants, such as vitamins A and C, can donate electrons to these free radicles and inactivatete them
how are free radicles produced
free radicles can be produced via exposure to radiation or via toxin ingestion
state how free radicles can be used in immunology
- free radicles are formed by the actions of certain enzymes in some cells (eg - WBC’s)
- free radicles remove electrons from outer shells of atoms in the cell wall/cell membrane of pathogens to become stable, in turn breaking down pathogens
define what it is meant by the key term ‘solute’
a solute is something that can be dissolved in a liquid
define what it is meant by the key term ‘solvent’
a solvent is a liquid at which solutes can be dissolved in
define what it is meant by the key term ‘solution’
a solution is the product of solutes being dissolved into a solvent
define what it is meant by the key term ‘acids’
acids are molecules which release hydrogen ions/protons
define what it is meant by the key term ‘a base’
- a base is any substance which is able to accept hydrogen ions/protons
- consequently, bases decrease the proton concentration in water
- define what it meant by the key term ‘strong acid’
a strong acid is an acid which completely, or nearly completely, becomes fully ionised in solution
define what it is meant by the key term ‘acidity’
acidity refers to the concentration of free/unpaired protons/hydrogen ions in a solution
define what it is meant by the key term ‘pH’
- pH is the negative logarithm to the base 10 of the hydrogen ion/proton concentration
- pH = -log(H+)
- for example, 10-7 mol/l = pH7
what is the usual homeostatic pH range
7.35-7.45 pH
define what it is meant by the key term ‘concentration’
concentration is the amount of a solute present within a unit volume of solution
how is concentration expressed when the chemical structure of a molecule is known
when the chemical structure of a molecule is known, concentration is expressed based upon the number of solute molecules in solution, using the measurement of mass called the ‘molecular weight’
define what it is meant by the key term ‘molecular weight’
- molecular weight is the sum of all the atomic masses of all the atoms within that molecule
- eg - glucose molecular weight = 180
what is the value of ‘Avogadro’s number’
6 x 10^23
what does ‘Avogadro’s number’ state
- Avogadro’s number states that 1 mole of any molecule will contain the same number of molecules as any other molecule
- therefore, 1 mol/l glucose will contain the same number of molecules as 1 mol/l any other molecule
