- Created by: stesar
- Created on: 19-11-17 14:14
Relative Charge Relative Mass
Protons +1 1
Neutrons 0 1
Electrons -1 1/200
NUMBER OF PROTONS = NUMBER OF ELECTRONS
NUMBER OF NEUTRONS = MASS NUMBER - ATOMIC STRUCTURE
Electrons within each shell will not have the same amount of energy. The energy levels/ shells are broken down into sub-shells called orbitals (these have different states).
Writing out electron structure
- Half arrows represent each electron
- Each orbital has a different spin state
- Since electrons repel each other, they fill up singularly first
Ions - lose or gain electrons
Loses = + e.g Al 3+
Gain = - e.g O 2-
1) State the name of the force between ions.
2) State the meaning of the term electronegativity
The ability of an element/ atom in a molecule, to attract a bonding pair of electrons
3) State three factors that affect the electronegativity of an element
1 - atomic radius
2 - nuclear charge
3 - the number of shells
Reactants -> products = same number of moles
2Mg + O2 -----> 2MgO
1 2 Mg = 1 2
O = 2 O =
H2SO4 = Sulfuric acid
HCl = Hydrochloric acid
HNO3 = Nitric acid
_____ CO3 = _____ carbonate
_____ (OH-) = _____ hydroxide
Moles and Molecular Masses
Mass of an atom is compared to carbon-12 = relative atomic mass
R.A.M = Ar
E.g. CO2 - C=12 + O2 = 16x2 = 44, R.A.M
R.F.M = Mr
One moles has 6.023x10(23) particles in it
MOLAR MASS OF A SUBSTANCE = SAME AS THE MASS OF ONE MOLE OF A SUBSTANCE
E.g. 12g of C = 1 Mole
16g of O = 1 Mole
a) If 9g od Aluminium reacts with 35.5g of chlorine, what's the expected formula of the compound?
Step 1: divide the mass of each element by its' R.A.M
Al: Moles = mass/RAM = 9/27 = 0.3 moles
Cl: moles = mass/RAM = 35.5/35.5 = 1 mole
Step 2: Divide each answer by the smallest number
Al: 0.3 moles - 0.3/0.3 = 1
Cl: 1 mole - 1/0.3 = 3
E.g the empirical formula of a hydrocarbon is CH2 and its Mr is 42
CH2 - C = 12, H2 = 1x2 = 2 =RAM - 14
Mr = 42
42/14 = 3
Moles and Concentrations
When 1 mole of a solute is dissolved in 1dm3 of solution its concentration is 1mol dm3.
e.g 1 mole of HCl = 1+35.5 = 36.5g, When 1 mole of HCl is dissolved in 1dm3 of solution, the concentration is 1mol dm3
MOLE (mol) = MOLARITY (M) / VOLUME (dm3)
The amount of product made in a chemical reaction is called its yield. The percentage yield tells us the amount of product that's made compared to the maximum amount that could be made.
Very few chemical reactions have a yield of 100% because:
- Reactions may not be pure
- Some products may be left behind
- Reaction may not have completely finished
- Some reactants may give some unexpected products
- Reactions may be reversible
PERCENTAGE YIELD = ACTUAL MASS/ THEORETICAL MASS x100
= ACTUAL NUMBER OF MOLES/ x100 EXPECTED NUMBER OF MOLES
Transverse - particles that move at right angles to wave propagation (EM waves)
Longitudinal - particles that move in the same direction, back and forth as the wave propagation
Energy of Waves
Energy transported by a wave is directly proportional to the square of the amplitude of the wave.
(f) Frequency - number of oscillations per unit time
(s) Speed - the distance travelled per unit time - a scalar
(v) Velocity - the displacement per unit time - vector
VELOCITY = WAVELENGTH X FREQUENCY
Polarisation of transverse wave = cuts out any wave moving as a displacement
Diffraction is the spreading of waves as they go through a gap or round an edge, E.g. radio wave, sound
Wavelength - distance between two consecutive points where oscillations are in phase with one another
Period - time for one complete cycle
Amplitude - maximum displacement always measured from the central 'rest' or 'equilibrium' point
A standing wave that is confined between boundaries. With all waves, resonance and natural frequency are dependent on reflections from boundaries of the system containing the wave. The two waves (initial wave and reflected wave) interfere to produce constructive and deconstructive interference.
Condition of Refraction
1) The wave must change speed when crossing the boundaries
2) The wave must approach the boundary at an angle
Why do refractions occur?
When a wave passes through a denser medium, they slow down. As the velocity of a wave decreases, its wavelength must decrease.
Amount of refraction depends on - angle at which the light meets the surface - amount of difference in density - measured by quantity
Fibre Optics: Endoscopes
Endoscopes are optical instruments that can be inserted into the body to examine body organs.
Light is piped in using a small bundle of optical fibres, with the image being focused by an objective lens.
Some shorter rigid tubular endoscopes use a series of relay lenses.
Longer flexible 'fibrescopes', the image is conveyed by a second fibre bundle back to an eyepiece.
Each fibre bundle consists of -core, cladding, protective plastic buffer coating
The image transmitted is pixelated. Each fibre produces just one dot of colour so the resolution depends on the number of fibres in the bundle.
- Types of light
- Speed in vacuum = 300,000 km/sec
- Speed in other materials = slower in air, water, glass
Transverse Waves Energy is perpendicular to direction of motion
Moving photon creates an electric and magnetic field - light has both fields at right angles! - wire with an electrical current, it will generate a magnetic field
Speed of the Waves
All electromagnetic waves travel at the same speed in a vacuum = 300,000,000 ms(-1)
To calculate the energy of a wave - E = h f
(E - Energy, h - Planks constant, f - frequency)
Wave Uses Dangers
Radio radio, TV None
Microwaves Mobile phone network Internal tissue heating
Infrared Cooking, TV remotes Skin Burns
Light Telescopes Damaging eye-sight
Ultra-violet food-processing, sun-beds High dose: kills cells, low dose: cancer cells
X-Rays Medicine Same as above
Gamma Rays Cancer Treatments Same as above
- High power over long distances.
- Higher power networked system.
- Radio -> microwave borderline.
- Higher frequencies, greater data capacity.
- A low power device, small range.
- Early Bluetooth devices interfered with Wi-Fi devices because both would use the same channel for an extended period.
- Range from 10-100m
- Radio -> microwave frequencies
- Low power devices to device link
- The longer wavelength band is better because it doesn't suffer from 'sunlight blinding'
Eukaryotic = Plant and animal
- Outer Membrane
- Cell wall
Prokaryotic = bacteria and ardiabacteria
- No nucleus
- Outer membrane
- Cell Wall
Magnification = size of image/ actual size of object
Palisade Mesophyll (at the top of the leaf to get sunlight)
- Cell membrane
- Cell wall - support
- Chloroplast - photosynthesis
- Tail - to move sperm
- Acrosome - penetrates the egg cell membrane - half genetics and enzymes
- Midpiece - contains mitochondria and energy to travel
Egg Cell - largest cell in the body
- Nucleus - containing 23 chromosomes
- Corona radiatia
- Zona palliada
- Special vesicles - contains substances to stop more than 1 sperm penetrating the cell
- Supply nourishments to the growing embryo
Root Hair Cell
- Nucleus, cell membrane, cell wall
- Thin walls to allow more to come into the cell
- Mitochondria - large amount
- Vacuole - stores energy and waste, larger than normal
- Cytoplasm - holds cell together
- No chloroplast, doesn't photosynthesis
White Blood Cells
- Nucleus - signal other molecules - control/ code the protein
- Cytoplasm - make it possible for the cell to change shape
- Cell membrane
Red Blood Cells
- Cell membrane
- Made in bone marrow
- No nucleus - room for more haemoglobin
- Big surface area - more volume
The actual power or magnification of a compound optical microscope is the product if the powers of the ocular (eyepiece) and the objective lens. The maximum magnifications of the ocular are 10x, giving a final magnification of 1000x. The minimum resolution is 200 nanometers, due to the wavelength of light.
A scanning transmission electron microscope has achieved better than 50pm resolution and a magnification of up to about 10,000,000x
Nucleolus - manufacturers ribosomes within the nucleus
Ribosomes - translates mRNA into protein
Cell Wall - provides structural support and protection from high turgor pressure
Rough ER - the site of protein synthesis
Golgi Apparatus - processing and packaging of proteins
Mitochondria - generates ATP by aerobic respiration
Squamous Epithelial Tissue
- Thin - rapid diffusion
- One cell thick
- Lining tissue - keep certain things apart so don't mix
- Made from flattening squamous epithelial cells
- Cells from smooth, thin, flat layers
- Found in the lining of the alveoli in the lungs - gas exchange, thin, moist, lots of blood vessels
Ciliated Columnar Epithelial Tissue
- Column-shaped ciliated cells
- Cilia - wall-like structures
- Protect against infection by sweeping pathogens out of the lungs
- Goblet cells - secrete mucus
Effects of Smoking
- Damage squamous cells
- inflammation -build up of tissue fluid
- scarring - larger diffusion distance
- walls become thicker
- more mucus produced
- damage causes emphysema and loss of elasticity
Skeletal - overall the skeleton - essentially voluntary movement, attached to bone by tendon, sends messages to central nervous system to tissue
Cardiac - found in ventricle and atrium walls in the heart - contract rhythmically throughout lifespan, doesn't fatigue
Smooth - found in the lining of organs, especially the digestive system - rhythmically contract, slow to fatigue, involuntary
Fast Twitch (oxidative) - regions of skeletal muscle - more mitochondria, myoglobin and blood capillaries, relatively resistant to fatigue
Fast Twitch (glycolytic) - regions of skeletal muscle - less myoglobin, few mitochondria, few capillaries, large concentration to glycogen, contract quickly = fatigue quickly
Slow Twitch - some regions of skeletal muscle - used in endurance, contract slow, fatigue quick
Function - carry electrical messages
- Sensory - carry messages from receptor to CNS
- Motor - carry messages from neurone to whatever need to do an action
- Relay - connect sensory and motor neurones
Action Potential - electrical messages sent along neurones
- Myelin Sheath - thick insulating layer around axon
- Node of Ranvier - gap in the myelin sheath where axon is exposed
- Axon - long single fibre that carries nerve impulses
- Dendrites - highly branched fibres that conduct impulses
- Schwann Cell - wrapped around axon, forming myelin sheath
How do neurons operate?
Resting Potential - neurone at rest
- A neuron is said to be polarized
- Neuron has a voltage difference of -70mV (difference between inside and outside)
How it is maintained
Sodium-potassium pumps inside the axon, pumps 3 sodium ions for every 2 potassium ions out
At rest, the sodium gates are closed. The membrane is 50x more permeable to K- ions, causing them to leak out.
Depolarization and Repolarization
Action potential occurs at two stages:
- Depolarization - when a neuron is excited pass it's threshold = from -70mV to -50mV
- The sodium ions move into the axon, neutralising negative ions inside.
- The axon temporarily swaps charges (inside charge becomes outside charge, etc.)
- Nearby sodium channels open to continue depolarization
Repolarization - restoring the charge
- Potassium gates are opened, floods out, generating positive charge from outside of membrane
- Sodium channels close
- The sodium/ potassium pump rapidly moves sodium out of the cell, restoring charge to the original state.
Depolarization and Repolarization
Saltatory Conduction - the 'jumping' of an impulse between the nodes of Ranvier thus dramatically increasing its speed. This only occurs in the axons which have myelin
Brief period of time between the triggering of an impulse and when its available for another - no NEW action potentials can be created during this time (wait till its back to -70mV)
If an axon is stimulated above its threshold, it will trigger an impulse down its length.
The strength of the impulse is not dependent upon the stimulus.
An axon cannot send a mild or strong response. It either responds or it doesn't.
MORE NEURONES = STRONGER STRENGTH
An electrical impulse travels along an axon. This triggers the nerve-ending of a neuron to release chemical messages called neurotransmitters. These chemicals diffuse across the synapse (the gap) and bind with the receptor molecules on the membrane of the next neurone. The receptors on the second neurone bind only to the specific chemicals released from the first neurone. This stimulates the second neurone to transmit the electrical impulse.
The Cholinergic Synapse
The synaptic knob - a swelling at the end of the presynaptic membrane.
- Many mitochondria
- Smooth endoplasmic reticulum
- Vesicles containing acetylcholine
- Voltage-gated calcium ion channel in the membrane
Acetylcholine is an enzyme found in the synaptic cleft. It hydrolyses acetylcholine into ethanoic acid and choline is then taken back into the presynaptic membrane to form acetylcholine.
Transmission Across The Synaptic Cleft
1) Action potential arrives
2) Calcium channels open
3) Vesicles containing acetylcholine move into the presynaptic membrane
4) Vesicles fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft
5) Acetylcholine diffuses across the synaptic cleft to the postsynaptic membrane
6) Acetylcholine binds to receptors in postsynaptic membrane
7) Sodium channel ions open - the membrane is depolarised and an action potential is produced.