2. Chemistry Flashcards
Matter
Anything that takes up space and has mass
Two purity bases of matter
- Pure substance
2. Mixture
Pure substance
Only made of one type of material. e.g helium gas (only He)
Mixture
Made up of 2 or more different substances, can be operated by physical means. e.g H20 (hydrogen and oxygen)
Classification of matter
Atom
Element
Atom
Smallest unit of matter, cannot be cut, inseparable
Element
A substance made up of one type of atom and the properties of that substance
States of matter
Solids
Liquids
Gases
Solids
Definite shape and occupy definite volume
Strong forces of attraction, atoms don’t move much
Liquids
No definite shape, occupy definite volume
Lower force of attraction, molecules have more energy
Molecules slide across each other
Gases
No definite shape, no definite volume
Molecules had so much energy, they move too fast, breaking the forces of attraction
Two factors that influence states of matter
- Forces of attraction between molecules (strong/weak)
2. Molecules vibrate
Two categories for pure substances
- Element
2. Compound
Element
Atoms are the same (O2), (H2)
Cannot be broken down into two or more different substances. e.g oxygen
Compound
Atoms are different (CO2), (H2O)
A substance made up of two or more atoms which are from different elements.
Can be broken down into the elements contained in them
Two categories for Mixtures
- Homogenous mixture
2. Heterogenous mixture
Molecule
A substance made up of two or more atoms from either an element of compound.
Structure of an atom
Nucleus
Protons
Nuetrons
Electrons
Nucleus
Made up of a number of particles that are smaller than the atom
Protons
Positively charged particles in the nucleus
Number of protons determines what element the atom is
Neutrons
No charge
Subatomic particle in the nucleus
Help keep the nucleus together
Electrons
Negatively charged
Number of electrons is always equal to the number of protons
Atomic number
Number of protons that are present in an atom (top left corner) or top middle
Mass number
Number of protons + number of neutrons
Always a whole number
Atomic mass
Average of the number of protons and neutrons
Decimal number
Isotopes
An element that has the same number of protons but different number of neutrons
Electrons shells
Where the electrons are found
How many electrons in the first shell?
2
How many electrons in the second and third shell?
8
Valence shell
The outermost electron shell
Octet rule
The tendency to have 8 electrons in their second and third electron shell
Types of chemical bonds (4)
- Ionic bonds
- Covalent bonds
- Metallic bonds
- Hydrogen bonds
Ionic bonds
There is a physical exchange of an electron from the valence shell of one atom to the valence shell of another atom
Ion
When an atom has an unbalanced charge
Cations (t for +)
Ions that have a net positive charge (more protons than electrons)
Anions
Ions that have net negative charge (more electrons then protons)
Covalent bonds
Atoms achieve full valence shells by sharing electrons
Non-polar covalent bonds
Sharing of electrons is equal, so the resulting molecule has no charge associated with it. E.g carbon dioxide
Polar-covalent bonds
Sharing of electrons is uneven (electrons spend more time near one atom than the other)
Metallic bonds
Sharing of free electrons among a structure of positively charged ions
Hydrogen bonds
Weaker interactions that alter the way molecules interact with each other
Chemical reactions
The process which new bonds between atoms are formed, or where existing bonds between atoms are broken
Two components of chemical reactions
- Reactants - molecules present at the start
2. Products -molecules present at the end
Energy
The capacity for doing work/causing change
Two main forms of energy
- Potential energy
2. Kinetic energy
Potential energy
Energy store by matter due to its position
Chemical, electrical, nuclear
Kinetic energy
The energy associated with matter in motion
mechanical, thermal
Exothermic reaction (exergonic)
Chemical reactions that result in the release of energy
ex for exit
Endothermic reaction (endergonic)
reactions absorb energy in the form of heat. e.g ice pack on wrist
Types of reactions
REDS R - reversible E - exchange D - decomposition S - synthesis
Reversible reaction
Reaction can proceed in both directions
Exchange reaction
When one atom/functional group replaced another in a compound
Decomposition
A larger molecule is broken apart into simpler substances
Synthesis
two or more atoms/molecules are bonded together to form a more complex molecule
Metabolism
The chemical processes that occur within the cells of a living organism to maintain life
- Breakdown and assembly of molecules
- Reaction energy output or input
Catabolism
Breakdown of molecules
Anabolism
Building of molecules
Activation energy
The energy required to initiate a chemical reaction
Catalyst
A chemical substance that acts to lower the activation energy required for certain chemical reactions
Enzymes
Proteins that act as a catalyst
Mixtures
A combination of elements or compounds that are physically blended together
Solvent
A liquid or gas that is able to dissolve other substances
Solute
A substance that is dissolved into solvent
Solution
A mixture of a solute dissolved into a solvent, remains evenly distributed
Colloid
A mixture of a solute and solvent, but where the solute particles are large enough to scatter light as it passes through
Suspension
A mixture of particles in a liquid for a period of time, but eventually it will settle out of the liquid
Concentration
The proportion of solute dissolved in a solvent (high/low)
High concentration
High amount of solute
Low concentration
Low amount of solute
Terms to describe the concentration of a solute (3)
Mass
Percentage
Molarity: number of molecules present
Mole
Unit of measurement for amount of substance
Molecular weight/mass
Sum of the atomic weight/mass of all elements contained within the molecular that makes a compound
Molarity of a solution
Number of moles of solute dissolved in 1L of solvent
Acids
A substance that separates when dissolved in water and releases hydrogen ions
Bases (alkali)
A substance that separates when dissolved in water and releases hydrogen ions
Salts
Any compound that results from the chemical interaction of an acid and a base
Strong/weak acids
Strong acid - a substance that has a strong tendency to separate completely and release hydrogen ions
Weak acid - a substance that has a weak tendency to separate and release hydrogen ions
Strong/weak bases
Strong base - a substance that has a strong tendency to separate completely and release hydroxide ions
Weak bases - a substance that has a weak tendency separate to release hydroxide ions
pH (potential hydrogen)
Measure of the concentration of hydrogen ions in a solution
pH levels below 7 (<7) =
Acidic
pH levels of 7 =
Neutral
pH levels above 7 (>7) =
Basic (alkaline)
Buffer
A substance that is able to remove or ad hydrogen ions and is able to resist large changes in pH
Organic molecules
Those that contain the element carbon
Four types of organic molecules
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids and nucleotides
What compounds are carbohydrates?
Sugars
Glycogen
Starches
Cellulose
Function of carbohydrates
Source of chemical energy
The energy released when carbohydrates are broke down are the molecules of ATP
Three major groups of carbohydrates based on size
- Monosaccharides
- Disaccharides
- Polysaccharides
Monosaccharides
one saccharide molecule
mono = 1
Disaccharides
Molecules that are formed by the joining together of two monosaccarides
di = 2
Polysaccharides
Molecules that are formed by the joining together of tens or hundreds of monosaccharides
poly= many
Main polysaccharide in the body
Glycogen
Main polysaccharides produced by plants
Starches and Cellulose
Main types of lipids in the body
Fatty acids
Phospholipids
Steroids
Function of proteins
Form enzymes which catalyse chemical reactions in the body
Form antibodies to detect invading microbes
Dipeptide
Two amino acids joined together
di = 2
Tripeptide
Three amino acids joined together
tri = 3
Polypeptide
Tens of thousands of amino acids joined together
poly= many
Amino acids
Building blocks for proteins
Four levels of structural organisation of proteins
- Primary
2, Secondary - Tertiary
- Quaternary
Primary structure of a protein
Sequence of amino acids linked together by peptide bonds to form a polypeptide
Secondary structure of a protein
The repeated twists and folding that the polypeptide chain undergoes
Tertiary structure of a protein
Three dimensional folding pattern of a protein due to side chain interactions
Quaternary structure of a protein
The combination of different polypeptides to form a single functional protein
Denaturation
The breaking down of a protein three dimensional shape
Two forms of nucleic acid in the body
- Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
Three components of a nucleotide
- A nitrogenous base
- A sugar composed of 5 carbons
- A phosphate group
4 nitrogenous bases (nucleotides)
Thymine (T) - Adenine (A)
(the apple (A) falls of the tree (T))
Cytosine (C) - Guanine (G)
What is replaced in RNA
Uricil (U) replaces Thymine (T)
Function of ATP
Acts as a storage molecule for energy
Radiation
The travel of energy either as particles or as electromagnetic waves
Types of radiation
Ionising radiation
Non- ionising radiation
Ionising radiation
Has enough energy to strip electrons away from other atoms. e.g x-rays, alpha, beta, gamma rays
Non-ionising radiation
Can interact with materials but it does not have enough energy to move electrons. e.g microwaves
Nuclear radiation
The release of radiation due to the breakdown of an atoms nucleus
Types of radiation nuclear decay can produce
- Alpha rays
- Betta rays
- Gamma rays
Two types of radiation damage
Direct
Indirect
