Chemistry Flashcards
What are atoms?
Atoms are small particles of matter, that are made up of electrons, protons and neutrons
What is matter?
Matter is everything around us that has a mass and occupies space.
What is an element?
An element is a substance made up of just one type of atom so it cannot split up into simpler substances.
In chemistry each element is given a ? for it’s long name?
chemical symbol
What are the four major elements in the human body?
carbon, hydrogen, oxygen and nitrogen account for 96% of the human body.
Protons and neutrons together form what?
Nucleus of an atom.
Protons have a ? charge and a mass of approx.?
positive charge and mass of approx. 1.
Electrons are ? charged and have ? mass.
Negatively charged and have no mass at all.
Electrons move in groups around the nucleus known as?
electron shells
The number assigned to each element on the periodic table correlates to what?
The number of protons and electrons in each element.
How do you work out the number of neutrons?
Mass number - atomic number
What are isotopes?
Atoms of the same element which have different numbers of neutrons in the nucleus?
What is a stable element? Give an example.
It will have an equal number of electrons and protons giving an overall neutral charge. Hydrogen - one proton, one electron, no neutrons.
What do isotopes affect?
They change the mass of the element
Hydrogen only has one electron in it’s outer shell also known as? and what does this mean?
the valence electron. It will often go looking for another atom that needs one electron to fit it’s shell. This means H easily reacts with other atoms.
Elements which do not easily react because their outer shells are filled with perfect numbers are called?
Inert
If an atom gives up or gains electrons to stabalise it’s outer shell, it becomes what?
An ion.
Ionisation is the process of what?
giving or gaining electrons
Donating electrons to another element creates what type of charge?
Positive charge
Gaining electrons from another element creates what type of charge?
Negative charge
What is oxidation?
The removal of electrons from an atom or molecule.
Oxidation ? the potential energy of the compound.
Decreases
Generally, most oxidation occurs with the removal of?
Hydrogen
When something is reduced it ? electrons, resulting with the increase of energy in that molecule.
Gains electrons
When oxidation and reduction reactions happen together, it is known as ?
Redox reactions
What is the process of oxidation in the human body?
An energy releasing step, and is very important in the energy transfer in our human bodies.
What are free radicals?
Free radicals are molecules or compounds that have an unpaired electron in their outer shell.
Explain the chain reaction of free radicals and process of oxidative damage.
Because they want to stabalise their outer shell they become destructive and ‘steal’ electrons from other stable molecules - Oxidation. This leaves the attacked molecule with an unpaired electron, so a chain reaction of oxidative damage occurs.
What are antioxidants?
They consist of a group of vitamins, minerals, phytochemicals and enzymes that work to neutralise free radicals before they harm our bodies.
What types of things can cause oxidative damage?
Free radicals develop from processes within our bodies such as normal aerobic respiration, metabolism and inflammation. They can also come from the environment such as pollution, sunlight, strenuous exercise, x-rays, smoking and alcohol.
What is key to a good antioxidant?
It must be stable once it has given away it’s electron.
What is a molecule? Give an example.
A discrete group of atoms bonded together in a specific arrangement e.g H2O.
What is a compound? Give an example.
An electrically neutral substance containing two or more elements in a defined ratio. e.g NaCl (table salt)
Name the two types of bonding. Describe the difference
Electrovalence bonding (ionic bonding) where one element donates some of it's electrons to another. Covalent bonding when two elements share electrons so that they both have the 'magic' number.
Some elements have a lot of ‘pulling power’ (electronegativity). What are these bonds called?
Polar bonds
What do polar bonds do?
They are able to pull the electrons in a bond towards them creating an uneven distribution of charge where one part of the molecule is slightly positive and the other part slightly negative.
Which 4 elements are most electronegative?
Fluorine, Chlorine, Oxygen and Nitrogen
What is a hydrogen bond and where does it occur?
The attraction between the hydrogen and a negatively charged atom. It occurs in water.
Molecules which have polar bonds and dissolve easily in water are called?
Hydrophilic molecules
Molecules which contain non-polar covalent bonds so they do not associate easily in water are called?
Hydrophobic molecules
What is an electrolyte? Give an example.
An ionic compound. e.g salt when dissolved in a solution
Why are electrolytes important for the body constituents?
Because they conduct electricity essential for nerve and muscle function, they exert osmotic pressure important for fluid balance and play an important role in acid-base balance, acting as buffers.
What is an acid and what does it measure?
A substance that releases a high amount of H+ ions when dissolved in water. It measures acidity using the PH scale.
What is a base?
A substance binds hydrogen ions in solution. This creates lots of OH-.
What are buffers?
Substances that maintain the H+ ion concentration in the body within normal limits.
What does the law of conservation of energy say?
that energy is never lost, it only will change state
Name the energy states
Potential (stored) to kinetic (movement)
Chemical energy stored in bonds between different atoms
Energy can also change state into heat
Name the 4 states of matter
solid
liquid
gases
plasmas
Name the state of matter:
a definite shape, a definite volume and particles that are close together in a fixed arrangement
Solid
Describe a liquid state
an indefinite shape but a definite volume, the shape as their container and particles are close together, but mobile.
Describe a gas state
an indefinite shape, an indefinite volume, the same shape and volume as their container and particles are far apart.
What occurs when new bonds are formed or old bonds are broken between different molecules?
Chemical reactions
The stating materials are known as ? and the end molecules are known as ?
reactants, products
An ? reaction is one that takes in heat to use for energy.
Endothermic
An ? reaction release heat into the environment.
Exothermic
The minimum temperature that is required for a particular reaction is known as the ?
Energy of activation
Chemical reactions are reliant on which 2 things?
the correct temperature and a high enough concentration of reactants.
What else forces molecules closer together?
change in pressure
What is a catalyst and what does this mean?
Speeds up reactions by lowering the activation energy required. The reaction is faster or can occur at lower temperatures.
What are inhibitors and what does it mean?
Act antagonistically to catalysts, they stop the catalyst from being so effective making the activation energy higher again. This slows the reaction time down or means higher temperatures are needed to make the reaction ‘go’.
Anabolic reactions (synthesis) are generally?
Endothermic - take in heat
Catabolic reactions (breaking down) are generally?
Exothermic - release energy
When water is the medium that breaks down the molecule into smaller pieces is it known as a?
Hydrolysis reaction
When water is formed as the waste product of a reaction, it is known as a?
dehydration synthesis reaction
