3a. Chemistry - Elements, Atoms Flashcards
What is an atom?
Small particles that make up matter
like Lego bricks
What makes up an atom?
Protons
Neutrons
Electrons
What is an element?
A substance made up of just one type of atom
It can’t be split up into simpler substances
What is a molecule?
Two or more atoms bonded together
Not visible to humans
Examples of molecules
Oxygen (O2)
Carbon dioxide (CO2)
Nitrogen (N2)
What is a compound?
Two or more different elements bonded together
Visible to humans
Examples of compounds
Table salt (NaCl)
Vinegar (C2H4O2)
Methane (CH4)
How many different elements are normally present in the human body?
26
What are the 4 major elements found in the human body?
Carbon
Hydrogen
Oxygen
Nitrogen
What percentage of the human body is made up of the 4 major elements?
96%
Chemical symbol: Hydrogen
H
Chemical symbol: Sodium
Na
Chemical symbol: Magnesium
Mg
Chemical symbol: Calcium
Ca
Chemical symbol: Vanadium
V
Chemical symbol: Chronium
Cr
Chemical symbol: Manganese
Mn
Chemical symbol: Iron
Fe
Chemical symbol: Cobalt
Co
Chemical symbol: Nickel
Ni
Chemical symbol: Copper
Cu
Chemical symbol: Zinc
Zn
Chemical symbol: Molybdenum
Mo
Chemical symbol: Mercury
Hg
Chemical symbol: Boron
B
Chemical symbol: Carbon
C
Chemical symbol: Nitrogen
N
Chemical symbol: Oxygen
O
Chemical symbol: Fluorine
F
Chemical symbol: Aluminium
Al
Chemical symbol: Silicon
Si
Chemical symbol: Phosphorus
P
Chemical symbol: Sulfur
S
Chemical symbol: Chlorine
Cl
Chemical symbol: Selenium
Se
Chemical symbol: Iodine
I
Proton: charge and weight
Positive
1 atomic unit
Neutron: charge and weight
No charge
1 atomic unit
Electron: charge and weight
Negative
No weight
Structure of an atom
Nucleus - made up of equal protons and neutrons Electron shell(s) - made up of electrons
How do electrons arrange themselves in the electron shell?
Pairs
2-8-8
What makes an atom reactive?
If the outer electron shell isn’t full or if it loses an electron
Atom analogy
Each proton is an adult with one child (electron)
Each neutron is an adult with no children
The adults hang out together in the nucleus and make up the mass of the family
The children whizz around the adults not weighing anything
Each proton has a positive charge
Each electron has a negative charge
These opposites attract each other and keep the family together
Periodic table example
19 (atomic number)
K (element symbol)
Potassium (element name)
39.0983 (atomic mass)
What is the atomic number of an element?
The number of protons
What is the mass number of an element?
Number of protons + number of neutrons
How can you calculate the number of neutrons in an element?
Atomic mass - atomic number
What element is required for thyroid health?
Iodine
Why are fluoride and chlorine relevant in thyroid health?
They share similar chemical and physical properties to iodine (same column on periodic table)
If they are present in the body, they can prevent the formation of T3 and T4
Where can we find fluoride?
Tap water
Toothpaste
Mouthwashes
Where can we find chlorine?
Swimming pools
Chlorinated washed vegetables
What is an isotope?
Atoms of the same element which have different numbers of neutrons in the nucleus
What affect does an isotope have on an element?
Changes the mass
Doesn’t affect the chemical activity though
What does a massive imbalance of protons and neutrons create?
Makes the atom very unstable
What does an imbalanced isotope cause?
Radioactivity
Examples of isotopes in medicine
Radiotherapy
Breath test for H. pylori
How does the breath test for H. pylori work?
Breath test 1
Take urea - labelled as radioactive carbon-14 or non-radioactive carbon-13
Wait 10-30 mins
Breath test 2
If urease is present (enzyme that H. pylori uses to metabolise urea), there will be a higher amount of CO2 in 2nd breath test
What does H+ mean?
It’s a hydrogen ion
It’s a proton as the electron has become separated from the outer shell
Why does hydrogen easily react with other atoms?
Because H has only one electron in its outer shell, it will often go looking for another atom that needs one electron to fill its shell
What are inert elements?
Elements that don’t easily react as they have their outer shell filled with the perfect number
They rarely get involved in chemical reactions
Why do atoms try to bond?
To get the right number of electrons in their outer shell so they can become more stable
What are the two types of bonding?
Ionic bonding
Covalent bonding
What is ionic bonding?
When one atom donates some of its electrons to another
When does ionic bonding usually occur?
When there are 1, 2 or occasionally 3 electrons to donate
What is ionisation?
The process of giving or gaining electrons
What is an ion?
An atom that has given up or received electrons to fill its outer shell
How is an ion written?
With their corresponding - or + charge
How do you write a sodium ion if it has given an electron away?
Na+
What is a covalent bond?
When two elements share electrons so that they can both have the magic number of electrons they are looking for
When does covalent bonding tend to occur?
When the two atoms are similar
When there are a lot of spaces to be filled to reach a full outer shell
Between what type of atoms does ionic bonding occur?
Atoms that have different electronegativity
Ions that are oppositely charged
What is a polar covalent bond?
When atoms with different electronegativities share electrons in a covalent bond but one of the elements has more electronegativity which pulls the shared electrons towards themselves
What makes an element more electronegative?
Having lots of protons
a strong positively charged centre
What does a polar covalent bond lead to?
An uneven distribution of charge
Which elements are the most electronegative?
Chlorine
Fluoride
Oxygen
Nitrogen
What is one of the most important examples of a polar bond?
The bonds between O2 and H in water
What happens during a O2 and H polar bond?
The O2 pulls the electrons towards itself resulting in a negative charge over the oxygen and a positively charged area over each hydrogen
The positive hydrogens on one water molecule are attracted to the negatively charged oxygens on the next molecule
What are the interactions between the O2 and H molecules called?
Hydrogen bonds
What qualities do the hydrogen bonds give to water?
Surface tension
Ability to dissolve many substances
Why is water considered to be the universal solvent?
The polar bonds are ideal for dissolving chemicals into their separate ions
The different electrical charges allow water molecules to become attracted to other molecules (hence why water dissolves salt/sugar)
What are hydrophilic molecules?
Polar bonds
Dissolve easily in water
(e.g. alcohol)
What are hydrophobic molecules?
Non-polar covalent bonds
Don’t dissolve easily in water
(e.g. fats)
What is an electrolyte?
An ionic compound that dissolves in water
e.g. salt
What do electrolytes do?
Conduct electricity
What are the key electrolytes in the body?
Sodium Potassium Magnesium Bicarbonate Chloride Calcium Phosphate
Why are electrolytes important?
Conduct electricity for nerve/muscle function
Exert osmotic pressure for water/BP balance
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+ in a solution
Creates lots of OH- (hydroxide)
Why is water a neutral solution?
For every H+ released, a OH- is also created
What is the pH of water?
7
What is the optimal pH of blood?
7.35-7.45
What is the optimal pH of the stomach?
2-3
Why are fruit and veg acidic before consumption but alkaline after?
Their organic acids are metabolised by the body and intestinal bacteria to become alkaline
They are also high in alkaline minerals e.g. K, Mg, Ca
Why is meat and dairy more alkaline before consumption but acidic after?
High protein/sulphur amino acid content
The sulphur amino acids increase sulphuric acid formation
What happens when sulphuric acid is increased in the body?
Disrupts blood pH
Calcium is drawn from the bones
Increased calcium is then lost in urine
What other foods are acidic apart from dairy and meat?
Refined sugars
Processed foods
What can also contribute to an acidic environment?
Stress
Sedentary lifestyle
Which pathology thrives in an acidic environment?
Cancer
What level of pH or above could start to kill cancer cells?
8
How can body acidity be measured?
pH test of urine or saliva
How do you do a urine pH test?
Urinate onto strip of pH paper
2nd urine output of the day
Measure pH midstream
How do you do a saliva pH test?
Wash mouth with plain water upon waking
Wait 10 mins
Spit onto pH paper
What pH do many cancer patients have?
4.5-6
What should your pH be ideally?
Neutral (7) or slightly alkaline
What creates a chemical reaction?
When different molecules form new bonds or break existing ones
What does every chemical reaction involve?
Transfer of energy to stored energy
Kinetic energy
Heat
What are the starting materials of a chemical reaction called?
Reactants
What are the end products of a chemical reaction called?
Products
How are chemical reactions written in formula?
A+B = AB
What does endothermic mean?
Takes in heat
What does exothermic mean?
Gives off heat
How do chemical reactions occur?
Two molecules need to collide (collision theory)
What can speed up the chance of a chemical reaction?
Number of molecules
The energy of the molecules (faster)
Temperature
Pressure changes
What is the energy of activation?
The minimum energy that is required for a reaction to take place
What does a catalyst do?
Speeds up reactions by lowering the energy of activation
How can catalysts benefit reactions?
Means the reactions are faster
Can also happen at lower temperatures
What are catalysts in the body called?
Enzymes
What are inhibitors?
They stop catalysts from being so effective
Make the activation energy higher so slows down the reaction time
Example of an inhibitor drug
Statins
HMG-CoA reductase inhibitors
What are anabolic reactions?
Building
Making new substances
Building new bonds
A+B = AB
What does an anabolic reaction require?
Energy
What are catabolic reactions?
Breaking down (e.g. breaking down food and releasing energy for storage)
AB = A+B
What is hydrolysis?
A catabolic reaction where water breaks down molecules into smaller pieces
What is a dehydration synthesis?
When water becomes a waste production of a reaction
e.g. when glucose bonds come together to form a carbohydrate
What are reversible reactions?
Reactions where the products of the reaction can react together to produce the original reactants
Helps maintain homeostasis
What is a buffer?
Substances that maintain the H+ concentration in the body within the normal limits
What does the bicarbonate buffer system do?
Mops up excess acidity
What happens during the bicarbonate buffer system?
CO2 from respiration reacts with H2O in blood and creates carbonic acid (H2CO3)
This quickly dissociates to form bicarbonate and hydrogen ions (HCO3- and H+)
How are excess H+ mopped up?
Increased breathing rate to exhale CO2 through lungs
Kidneys produce HCO3- buffer to excrete excess H+
Why do kidneys struggle with high acidity?
Kidney buffering system is fairly slow and puts strain on the organs
What is oxidation?
The removal of electrons from an atom or molecule
How does oxidation effect the potential energy in a compound?
It reduces it
What element usually helps with oxidation?
Hydrogen
What is a dehydration reaction?
When hydrogen electrons are lost during oxidation
What happens during a reduction reaction?
Electrons are gained
What does gaining an electron do to the potential energy of a molecule?
Increases it
What does OIL RIG stand for?
Oxidation Is Losing
Reduction Is Gaining
What are free radicals?
Molecules or compounds that have an unpaired electron in their outer shell
How do free radicals try to stabilise their outer shell?
By stealing electrons from other stable molecules
Why are free radicals destructive?
By losing an electron, this causes oxidation
The attacked molecule then becomes unstable and so on
Leads to a chain reaction of oxidative damage
Why is taking electrons from DNA destructive?
Damages genes
Can result in cancerous changes
Which conditions can oxidative damage lead to?
Cancer
Atherosclerosis
Fibromyalgia
Neurodegenerative diseases
How can free radicals develop?
Aerobic respiration Inflammation Metabolism Pollution Sunlight Strenuous exercise X-rays Smoking Alcohol
How can free radicals be mopped up?
Reduce exposure to the production sources of free radicals
Optimise antioxidant status
What are antioxidants?
Groups of vitamins, phytochemicals and enzymes that donate an electron to the free radicals
This converts them to harmless molecules without being damaged themselves
Examples of antioxidants
Beta-carotene Vit C Vit E Quercetin Glutathione
Why do antioxidants work better together?
They recycle each other
Why is it better to get antioxidants from food rather than a supplement?
Food substances contain a mix of AO
Supplements may lead you to take too much of one particular one
What are functional groups?
Groups of atoms that are attached to a carbon skeleton
What do functional groups do?
Contribute to the structure and function of a molecule
Determines how they behave
What are the characteristics of the hydroxyl functional group?
R-O-H Alcohols Polar Hydrophilic Dissolve easily in water
What are the characteristics of the sulfhydryl functional group?
R-S-H
Found in protein chains (amino acid cysteine)
Polar
Hydrophilic
What are the characteristics of the carboxyl functional group?
R-C-OH=O
Found in amino acids
Hydrophilic
Weak acid/negative particle
What are the characteristics of the amine functional group?
R-N-H-H
Found in amino acids
The -NH2 group can act as a weak base (alkalising) if necessary mopping up H+
What are the characteristics of the esters functional group?
R-C-OR’=O
Predominate bond in triglycerides
What are the characteristics of the phosphates functional group?
R-O-P-OH-OH=O Found in ATP Very hydrophilic Dissolve easily in water Forms a double negative charge