# Applied Science - Unit 1

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• Created by: stesar
• Created on: 19-11-17 14:14

## Atomic Structure

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

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## Orbitals

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-

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## Exam Questions

1) State the name of the force between ions.

Electrostatic force

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

2 - nuclear charge

3 - the number of shells

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## Balancing Equations

Reactants -> products = same number of moles

1)

2Mg   +   O2   ----->   2MgO

Mg = 1 2                    Mg = 1 2

O = 2                         O = 1 2

H2SO4 = Sulfuric acid

HCl = Hydrochloric acid

HNO3 = Nitric acid

_____ CO3 = _____ carbonate

_____ (OH-) = _____ hydroxide

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## 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

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## Empirical Formula

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

= AlCl3

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## Molecular Formula

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

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## Reacting Masses

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)

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## Percentage Yield

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

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## Waves

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

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## 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

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## Stationary Waves

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

Standing Wave

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.

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## 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.

Refractive Index

Amount of refraction depends on - angle at which the light meets the surface                                                                               - amount of difference in density                                                                                                 - measured by quantity

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## 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.

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## Electromagnetic Waves

• 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)

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## Electromagnetic Spectrum

Wave                      Uses                                     Dangers

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

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## Applications

Satellite Communications

• High power over long distances.
• Microwaves.

Mobile Phones

• Higher power networked system.
• Higher frequencies, greater data capacity.

Bluetooth

• 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.
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## Applications

Wi-Fi

• Range from 10-100m

Infrared

• Low power devices to device link
• The longer wavelength band is better because it doesn't suffer from 'sunlight blinding'
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## Cell Structure

Eukaryotic = Plant and animal

• Nucleus
• Outer Membrane
• Ribosomes
• Cell wall

Prokaryotic = bacteria and ardiabacteria

• No nucleus
• Outer membrane
• Ribosomes
• Cell Wall
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## Magnification Calculations

Magnification = size of image/ actual size of object

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## Specialised Cells

Palisade Mesophyll (at the top of the leaf to get sunlight)

• Cell membrane
• Cell wall - support
• Cytoplasm
• Nucleus
• Vacuole
• Chloroplast - photosynthesis

Sperm Cell

• Tail - to move sperm
• Nucleus
• Acrosome - penetrates the egg cell membrane - half genetics and enzymes
• Midpiece - contains mitochondria and energy to travel
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## Specialised Cells

Egg Cell - largest cell in the body

• Nucleus - containing 23 chromosomes
• Cytoplasm
• 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
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## Specialised Cells

White Blood Cells

• Nucleus - signal other molecules                                                                                                              - control/ code the protein
• Cytoplasm - make it possible for the cell to change shape
• Cell membrane
• Ribosomes

Red Blood Cells

• Cell membrane
• Cytoplasm
• No nucleus - room for more haemoglobin
• Big surface area - more volume
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## Microscopes

Light microscopes

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.

Electron microscopes

A scanning transmission electron microscope has achieved better than 50pm resolution and a magnification of up to about 10,000,000x

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## Functions

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

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## Tissue

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
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## Effects of Smoking

• Damage squamous cells
• irritation
• inflammation -build up of tissue fluid
• scarring - larger diffusion distance
• walls become thicker
• more mucus produced
• damage causes emphysema and loss of elasticity
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## Muscles

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

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## Neurones

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
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## How do neurons operate?

At rest:

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.

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## 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.
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## 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

Refractory Period

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

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## Synapse

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.

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## The Cholinergic Synapse

The synaptic knob - a swelling at the end of the presynaptic membrane.

It contains:

• 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.

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## 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.

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