Science Unit 6

Science

Brain & Mind

Reflex Arc; Reflexes

• Simple reflexes are what babies are born with; these include:- Rooting Reflex: stroking a baby’s cheek and it will turn towards your finger- Sucking Reflex- Swallowing Reflex

• More adult reflexes are things like:- Pupil Reflex- Blink Reflex- Cough Reflex- Knee-jerk Reflex

Reflex Arc

• The stimulus is detected by a SENSORY NEURON.

• Nervous impulses are carried along a RECEPTOR CELL to your CNS (Central Nervous System).

• The CNS is made up of your brain and spinal cord. It coordinates your body’s responses.

• Nerve impulses are carried along a MOTOR NEURON to an EFFECTOR. The effector carries out the response to the stimulus.

Baby Reflexes

• Stepping – 2/3 months

• Gasping – 9/12 months

• Startle – 3/6 months

• Sucking – 2 months

• Rooting – 4 months

• Swimming – 6 months

Conditioned reflexes

• Pavlov’s dog is a prime example of conditioned reflexes and behaviour. He rung a bell near his dog when the dog was eating. After a while, when Pavlov rung the bell, the dog’s mouth started to salivate because the noise of the bell reminded him of food.

Synapses

• Synapses are tiny gaps in between Neurons that transmits nerve impulses from one Neuron to another by means of chemicals diffusing across the gap.

• Serotonin – A chemical released at one type of synapse in the brain; resulting in feelings of pleasure.

• Prozac – A brand name for an Anti-depressant drug. It increases the concentration of Serotonin at the Synapses in the Brain.

• Ecstasy – A recreational drug that increases the concentration of Serotonin at the Synapses in the Brain, giving pleasurable feelings. Long-term effects include destruction of the Synapses.

The Brain

Left Side

• Logic

• Reason

• Objective

• Verbal

• Self-orientated

• Categorical

• Detail focused

• Mimicry

• Purposefulness

Right Side

• Intuition

• Emotions

• Subjective

• Visual

• Group-orientated

• Relational

• Whole picture focused

• Creativity

• Playfulness

Memory – Multi-Stone model

Stimuli

Touch Stone

Hearing Stone

Vision Stone

Processing Centre

Information you do not attend to; is lost.

RehearsalShort-termMemory

Long-term

Chemical Synthesis

Chemical Types

Bulk Chemicals

• Chemicals made by industries on a scale of thousands or millions of Tonnes per year.

Fine Chemicals

• Chemicals made by industry in smaller quantities then Bulk Chemicals.

Organic Chemicals

• Contains Carbon (C) – this means it’s covalent.

Mineral Chemicals

• Contains Ions – this means it’s Ionic.

ACIDS

• ALL ACIDS CONTAIN HYDROGEN!

• Sulphuric Acid

• Hydrochloric Acid

• Nitric Acid

• YOU NEED TO KNOWALL THREE OF THESE!

Rules for making SALTS

• Acid + Base Salt + Water

• Acid + Metal Salt + Hydrogen

• Acid + Carbonate Salt + Carbon Dioxide + Water

• They MUST end in ATE – For Example –Sulphuric Acid + Calcuim Oxide CalcuimSulphATE + Water

• Only exception is HCL (Hydrochloric Acid) – ends in an IDE!

Reactions

• 3 things to speed up a reaction:- Increase temperature- more concentrated reactants- Bigger surface area/ smaller particles.

• COLLISION THEORY- Reactions happen when two particles hit each other with enough energy to cause another product to be formed.- Higher the temperature give particles more energy to make collisions more likely (like how Enzymes work). - If the particles hit each other with lower energy than the activation energy. The reaction will not occur.

7 DIATOMIC ELEMENTS

Just to be clear about what elements there are:- Oxygen- Hydrogen- Chlorine- Fluorine- Bromine- Iodine- Nitrogen

These Elements travel around in pairs when they haven’t reacted with anything.

State Symbols

• These are easy (very easy):

• (s) – Solid

• (l) – Liquid

• (g) – Gas

• (aq) – Aquatic (means it has something to do with a liquid)

Writing A Chemical Equation

- Writing the word equationMagnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen

- Are there any Diatomic Elements? (previous slide)

- (put the State Symbols next to each element/solution) (s) (aq) (aq) (g)

- Is it balanced? (looking at groups in the periodic table).

Group 1 (+1)

Group 2(+2)

Group 3(+3)

Group 4X

Group 5(-3)

Group 6(-2)

Group 7(-1)

H Mg Cl

Is this a BALANCED equation?NO!

There is only one Cl on the left side and two on the right side, just the same as there is only one H on the right side.

Now the equation is balanced!

By adding 2HCL’s to equal to the 2 H’s and 2 Cl’s

Titration oh HCL against Sodium Hydroxide

• Pipettes are used to measure a precise volume of liquid. They can only measure one volume. For example, you get a 20cm³ pipette, a 10cm³ or a 5cm³ pipette.

• The Meniscus is how a water curves in a narrow tube

Titration oh HCL against Sodium Hydroxide - Continued

• Add 3 drops of indicator and swirl.

25cm³ Sodium Hydroxide (measured by pipette before adding the HCL in the pipette).

Synthesising Salts

• CHOOSING THE REACTION –1. Is it expensive? (everything in acid making is about the money £££)2. Is the reaction safe?3. Are any by products safe?4. How easy is it to obtain and transport the reaction?

CALCULATING PERCENTAGE MASS• Atomic Masses - Cu = 63.5g

- O = 16g- H = 1g- Cl = 35.5g

We now know all the masses of each reaction and solution. Now to find out the percentage.

CALCULATING PERCENTAGE MASSPart 2

• There will be a question in the exam where it tells you a theoretical yield (how much you should have gotten), but then the question says you made half of what you should have made, and you need to give a measurement of mass for an element or solution. This is how to do it:

Example question: How many grams of water did you get from this reaction?

Theory of neutralisation

• Acid: a substance that dissolves in water releasing H Ions (positive charge)

• Alkali: a substance that dissolves in water to release OH Ions (negative charge)

• This solution has been neutralised.

Waves

Introduction to waves

• The reason why we study waves is that they can transferenergy or information from one place to another.

• Electromagnetic Spectrum (difference in the waves, shorter the wave, the more deadly it is):

Different types of waves

• Transverse:

• Longitudinal wave:

Key Terms

• Amplitude (A) – how high the wave is from the centre.• Wave Length (λ) – this is the distance between two

corresponding points on the wave and is measured in Metres.

• Frequency – this is how many waves pass by every second and is measured in Hertz (Hz)

Wave Equation

Wave Speed (V) = Frequency (F)(Hz) x Wave Length (λ)(M)

Ways we can manipulate Waves

Reflection (badly drawn, it will always reflect at a 45˚ angle).

Refraction

Diffraction Interferance

Bending Light beams

• A beam of light gets refracted when it travels from one medium into another. This is because light travels slower in glass than it does in air.

Waves and Energy

• Low frequency – Long WavelengthRadio WavesMicro WavesInfraredVisible LightUltra VioletX-RaysGamma Rays

• High frequency – short wavelength.

Each of these types travels at the same speed through a vacuum (300,000,000 M/S), and different wavelengths are absorbed by different surfaces (e.ginfrared is absorbed very well by black surfaces). This absorption may heat material up like infrared and microwaves or cause an alternating current (like in a tv Ariel).

Going Digital

• T.V. And Radio signals can be sent in 2 different ways:

• Analogue – continuously varying amplitude

• Digital – amplitude can only be between 0 or 1.

• Analogue

• Digital

Advantage of Digital

• Carry more information

• Signals can be delivered with no loss of quality.

• Unlike analogue signals which can pick up alotof noise whilst been re-transmitted.

That’s it!

• GOOD LUCK TO ALL!