Science Notes 2010

8/2/2019 Science Notes 2010

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THE PERIODIC TABLE

ATOMS AND ELEMENTSDefinitions

Atoms: microscopic particles that make up all matter.

Protons: Subatomic particles within an atom. It has a positive charge (p+).

Neutrons: Subatomic particles within an atom. It has a neutral charge (no charge).

Electrons: Subatomic particles within an atom. It has a negative charge (p-).

Atomic number = number of protons = number of electrons. Distinguishes different elements.

Mass number = number of protons + number of neutrons.

Elements: basic building blocks of all matter. Atoms of the same element have the same amount of

protons

Molecule: a group of atoms bonded or joined together.

Lattice: a group of atoms bonding together in a network in a fixed ratio

Crystal lattice: an ionic structure that forms a large network of chemically bonded atoms.

Compounds: different elements that are chemically combined. They can either be identicalmolecules or a lattice.

Mixtures: A substance made up of two or more elements/compounds, it can be separated by

physical techniques.

# Note

- Opposite charges attract each other. So electrons can't spin away from the nucleus.- Atoms are mostly empty space and have a neutral charge.- Protons and neutrons are around 1800x larger than electrons.

ARRANGING THE ELEMENTSDefinitions

Groups: vertical columns. No. = electrons in outer shell.

Period: horizontal rows. No. = total amount of shells.

# Note

- Dmitri Ivanovich Mendeleev arranged the elements in order of atomic mass, he also put thefamilies into columns. Mendeleev left gaps for elements not discovered.

- John Newlands arranged the elements in order of increasing atomic mass.- Elements that belonged to the same family shared similar physical (colour. melting/boiling

points) and chemical properties (the way they reacted with other chemicals).

- Henry Moseley completed the modern periodic table, he suggested that physical andchemical properties were related to the atomic number, rather than mass.

- The most reactive metals are in the bottom left of the table, while the most reactive non-metals are in the upper right.

- Modern periodic table was made by Henry Moseley in 1913.THE ROLE OF ELECTRONSDefinitions

Shells: the area which electrons orbit around the atom, it is also known as energy levels.

Electronic Configuration: arrangement of electrons in the shells.


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Ion: A charged particle formed when an atom has lost/gained electrons

# Note

- Electrons determine all the chemical reactions that an atom takes part in.- Chemical reactions happen when atoms bump into each other and the electrons are taken

or given away or shared.- First Shell: 2, Second: 8, Third: 18 (can also be 8), Fourth: 32 (can also be 8). Outermost shell

must have 8. 2n^2 = electrons in shell.

- Number of shells an atom has is the same as that period number.- Group number is the same as the number of electrons on the outer shell except for

transition elements.

- Atoms react so that they can become stable like the noble gases (filled outer shell/8electrons), they can share, gain or lose electrons to become stable.

- When an atom lose electrons they become a positive ion.- When an atom gain electrons they become a negative ion.

METALS, NON-METALS AND SEMI-METALSDefinitions

Metals: an element that is inclined to give away its outer shell electrons, they are good conductors

of heat and electricity, lustrous, malleable and ductile. (Ion is positive)

Non-metals: an element that takes electrons from metals or share to become stable, they are poor

conductors, brittle and dull. (Ion is negative)

Metalloids (semi-metals): an element that takes electrons from other elements to become stable

and they can conduct electricity, acts like metals and non metals.

Electronegativity : the strength which an atoms holds its electrons.

# Note- The hydrogen atom can be either a positive or negative ion depending on which element it

meets. (Group 1 or Group 17)

- Helium could be placed in group 2 and 18 because it has 2 electrons on.- Two atoms of the same element bonded in gaseous form is a diatomic molecule.

FAMILIES OF ELEMENTSDefinitions

Noble gases: elements that don't react because they have a stable outer shell (may react in rare

circumstances), they are colourless. Also known group 8 or 18.

Halogens: tends to take electrons and they form molecules. Group 7 or 17.Alkali metals: tends to give electrons, react violently with water and it has metallic properties. Group

1.

Alkaline earths: Similar to group 1, but less reactive. Group 2.

Transition metals: they are hard elements, they have similar melting points (high) and they have

similar properties.


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CHEMICAL REACTIONS

WHAT ARE CHEMICAL REACTIONS?Definitions

Reactants: substances present at the start of a reaction.Products: new substances formed from a reaction.

Endothermic reactions: chemical reaction absorbing energy.

Exothermic reactions: chemical reaction releasing energy.

Solute: a substance that dissolves in solvent.

Solvent: the liquid the solute dissolves in.

Solution: a solute in a solvent.

Precipitate: a substance that doesn't dissolve when two clear solutions are mixed together.

Displacement: when 1 metal settles on top of another metal.

Spontaneous reactions: reactions that happen naturally, don't need much help to start and they will

continue by themselves.

Non-spontaneous: doesn't occur naturally and needs a continual supply of energy to keep going.

# Note

- You know if a chemical reaction has occurred if:1. gas if produced,2. heat/light/sound energy is created,3. colour change,4. a solid forms from a solution or a new substance has been formed.

- Physical change when a substance changes its state (liquid, gas and solid)- When an experiment gives off bubbles it's likely that it's giving off a gas.- In displacement the less reactive metal goes on top of the reactive metal.- Chemical bonds hold atoms in compounds together.

NAMING COMPOUNDSDefinitions

Electrostatic attraction: attraction between opposite charges.

Polyatomic ions (radicals): ions that are made up of more than 1 atom. Use brackets when more

than 1 radical is needed in a formula.

Covalent compounds: form when atoms share out shell electrons. It happens when non-metals

come together to become stable.

# Note

- Atoms are neutral while ions aren't.- Ionic compounds form when positive and negative ions attract each other and are linked by

electrostatic attraction. The links are called ionic bonds.

- When ions come together they create a compound which a total charge of 0 (stable).- Naming Ionic compounds: metal - non-metal compound, 2 elements only1. The positive ion is named first2. The positive ion takes its name from its parent element e.g. Na = sodium3. The negative ion takes its parents name and ads 'ide' at the end e.g. Chlorine = chloride- The charges of ions aren't included in the formulas, but their numbers are (they indicate

how many of each ion are in the formula).- Transition metals have a variety of ionic charges.


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- Metal ions; Group 1: +1 charge, Group 2: +2 charge, Group 3/13: +3 charge, Group 4/14:+4/+2 charge.

- Non-metal ions; Group 7/17: -1 charge, Group 6/16: -2 charge, Group 5/15: -3 charge,Group 4/14; -4 charge.

- To name a covalent compound: the first element in the formula is named, the secondelement is named like a negative ion, use prefixes toshow the number of atoms.

RADICALS

-

REACTION TYPESDefinitions

Combination reactions: when 2+ reactants combine to form 1 new substance.

Decomposition reactions: when a substance breaks down to form 2+ new substances.

Precipitation reactions: when 2 clear solutions are mixed to create a precipitate (insoluble solid).

Neutralisation reactions: base + acid = water +salt.

Combustion reactions: a reaction that involves burning oxygen.

Displacement reactions: when 1 metal deposits on another in a solution.

# Things to know

- In a displacement reaction the less reactive metal is on top.ACIDS AND BASESDefinitions

Acids: are compounds composed of hydrogen and other non-metal elements.

Bases: opposite of acids.

# Note

-

Strong acids give their hydrogen atoms away. Weak ones try to keep the hydrogen.

Number of

atoms

Prefix

1 No prefix or

mono-

2 Di-

3 Tri-

4 Tetra-

5 Penta-

6 Hex-

7 Hept-

8 Oct-

9 Non-

10 Dec-

Ion name: Formula:

Hydroxide OH-

Sulfate SO4 2-

Carbonate CO3 2-

Hydrogen carbonate HCO3 -

Ammonium NH4 +

Nitrate NO3 -


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- Properties of acids; sour, turns blue litmus red and they conduct electricity in watersolutions.

- Bases that dissolve in water are called alkalis.- Acid + metal = hydrogen + salt- Neutralisation reactions: Acid + hydroxide = salt + water. e.g. hydrochloric acid + sodium hydroxide > sodium chloride+ water. Acid + oxide = salt + water.- Acid + carbonate = salt + water + carbon dioxide. Acid + hydrogen carbonate = salt + water +

carbon dioxide. When the base is carbonate/hydrogen carbonate carbon dioxide is also

formed.

- pH scale ranges from 0-14. Acids have a pH less than 7. Bases have a pH higher than 7.Neutral substance (water) has a pH of 7. The pH scale measure the amount of hydrogen in a

solution. 0 has the most hydrogen while 14 has the least.

- Indicators show the pH of a solution. Some are: litmus (not precise) and universal indicator(precise).

ORIGIN OF THE UNIVERSE

THE EXPANDING UNIVERSEDefinitions

Doppler effect: the change in wavelength and pitch when the source passes a point.

Spectrum: a range of different light waves of various colours.

Hubble's law: distant stars and galaxies are going further away from us, the further they were the

faster they were going.

Big Bang: a theory that states all matter in the universe must have fitted inside a pinhead beforeexploding create the universe today.

# Note

- Doppler effect also happens with light but there's a change of colour instead of pitch.- Stars moving away are red shifted.- Stars moving towards us are blue shifted.- The positions of dark lines within a spectrum of light emitted by a star/galaxy determines

whether they are moving towards/away.

THE BIG BANG

Definitions

Big bang theory: states that the universe exploded in all directions from a single point (singularity),

containing lots of energy which was converted in matter and antimatter.

Dark matter: largely made of subatomic particles left over from the big bang, dark matter was

responsible for the drawing together of gas clouds.

Open universe: expands forever at a decreasing rate.

Closed universe: expansions stops and gravity drags everything back together and then they enter

black holes until all matter is packed into a single black hole.

Flat universe: stops expanding but will never reverse.

Accelerating universe: a universe that keeps expanding at an increasing rate because of a force

called dark energy.


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- The law of reflection states the angle of incidence is equal to the angle of reflection.

LENSES AND CURVED MIRRORS

Definitions

Convex lenses: curve outwards and are fatter in the middle.

Concave lenses: curve inwards and are thinner in the middle.

Principal focus or focus: where rays parallel to the axis meet or seem to meet in concave lenses.

Focal length: distance between focus and middle of the lens.

Real image: can be produced onto a screen.

Virtual image: can't be produced onto a screen.

Upright: the same way up as the original.

Inverted: upside down compared to original.

Enlarged: bigger than original.Diminished: smaller than original.

Magnified: image size divided by object size.

# Note

- When a ray passes through the centre of the lens it doesn't refract.

- In the diagram above, the object is at a distance greater than the focal length of the lenstherefore a real image is formed.

- In the diagram above, the object is at a distance less than the focal length of the lens there avirtual image is formed.

- Concave lenses only produce virtual images.


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- In telescopes: objective lenses produces a real, inverted image inside the focus of the

eyepiece lens which creates a virtual and enlarged image for the user.

- Concave mirrors: produces enlarged, upright virtual images of an object close to the mirror.Object is far from the mirror: real, inverted images are produced. Object is very far and

directly in front: real and small images are produced.

- Convex mirrors produce a smaller virtual image. .COLOURDefinitions

Dispersion: when white light is split into a spectrum.

Scattering: when gas and dust alter the direction of light. Raindrops also alter the direction which

creates rainbows.

Primary colours: red, blue and green.

Secondary colours: cyan, magenta and yellow.

Complementary colours: two colours of light that combine to make white. Red + Cyan. Green +

Magenta. Blue + Yellow.

# Note

- Using filters can remove colours from a ray of light. This is called coloursubtraction/absorption. It also occurs when we look at objects in different colours of light.

- We see the colours we see when light reflects off an object which absorbs all light but thecolour that is reflected, which reaches our eyes.


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- PAINTS: Blue paint absorbs red, orange and yellow light while it reflects green, blue andindigo. Yellow paint absorbs blue, indigo and violet while it reflects red, orange, yellow and

green.

THE FRAGILE CRUST

PLATE TECTONICS

Definitions

Pangaea: a continent made up of Gondwana and Laurasia.

Gondwana: made up of Australia, Antarctica, South America, Africa and India.

Laurasia: North America, Europe and most of Asia.

Crust: the rigid, rocky outer surface of the Earth, composed mostly of basalt and granite.

Lithosphere: made up of the crust and the upper part of the mantle.

Asthenosphere: layer of Earth that the lithosphere floats on, it has plastic properties and it is located

within the mantle.

Mantle: a rocky layer located under the crust, convection currents occur within the mantle.

Outer core: the liquid iron-nickel layer that surround the inner core.

Inner core: the solid iron-nickel centre of the Earth that is very hot and under great pressure.

Convection currents: the movement of hot rocks from lower mantle move to upper mantle which

causes the movement of tectonic plates.

# Note

- Alfred Wegner said there was a supercontinent called Pangaea.- Evidence that all continents were once together: fossils of the same plants and reptiles

were found across continents, structure and rock composition of mountains in North

America can be matched to those in Europe, ancient glaciers have left valleys and debris

across many continents which are now too warm to produce glaciers, coal has been found

above the Arctic Circle where it is far too cold for plants to grow and as lava from a volcano


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cools it adopts the magnetism of the Earth at that moment, these rocks found in South and

North America have been found with their north poles in different directions.

- Volcanic mountain ranges run down the centre of oceans, ages of the rocks of the oceanfloor are much younger than the rock of the continents, ocean trenches exist, rocks of

continents are less than the rock of the ocean floor and younger rock is next to ocean ridges

while the oldest is next to the ocean trenches.- Layers of the Earth: Lithosphere (crust and upper mantle), Asthenosphere, Mantle, Outer

Core and Inner Core.

-- Convection Currents


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AT THE EDGESDefinitions

Spreading boundaries: where plates move apart.Collision boundaries: where plates collide.

Transform/scraping boundaries: where plates scrape along each other.

Fault: a weakened line where ridges form.

Subduction zones: where a plate goes under another when they collide.

# Note

- Convection currents pushes ocean ridges apart and fills it with magma from the mantlewhich cools down when it comes in contact with water and creates underwater mountain

ranges. The edges of the plate go underneath others creating subduction zones.

- Heavier plate goes under. Oceanic plates are heavier than continental plates.- Ocean trenches form when oceanic plates drops below continental plates.- When 2 oceanic plates collide the faster one sinks. They form volcanoes and islands.- When 2 continental plates collide they form mountains. Because they both have similar

densities.

- Plates that scrape cause a lot of Earthquakes.EARTHQUAKESDefinitions

Focus: where an earthquake begins.

Epicentre: a point on the Earth's surface directly above the focus.

Seismic waves: vibrations that earthquakes produce.

Body waves: travel through the body of the Earth they are either primary (P) or secondary (S).

Primary waves: fastest wave, longitudinal/compression waves that push and pull the earth's crust up

and down and they can travel through solid and liquid rock.

Secondary waves: slower than P waves, they are transverse waves and have an up and down

movement. They hit the surface with a shaking motion, they will not travel through water.

Surface waves: travel on the surface of the Earth, they are either Love (L) or Rayleigh (R). These

waves are slower than body waves but they are stronger.

R waves: rolling waves, slowest but they are large and the most destructive. ROLLY DALMATIANS.

L waves: side to side motion, like a moving snake, they are the faster surface wave. LUCKY

DALMANTIANS.

Richter scale: increase of 1 unit represents 10x increase in size and 30x increase in energy. It

indicates the strength of an earthquake.

Mercalli scale: gives an indication of the damage caused by the earthquake.

Aftershocks: small earthquakes that are caused when slabs of crust and rock settle in after the initial

earthquake.

Tsunami: a wave caused by an earthquake occurring under the ocean floor.

# Note

- There's a lot of friction between plates and when they slip earthquakes occur.- P and S waves change direction and speed when passing through rocks of different densities.- To find the epicentre: calculate the time difference between the arrival of P and S waves,

then graph it on the graph, use the scale and then mark in on a map using a compass.


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VOLCANOESDefinitions

Volcano: a vent in the earth's crust that expels lava, steam and ashes.

Eruptions: when molten rock goes through the vent due to pressure from gases in the mantle.

Fume: clouds of steam and gas released by volcanoes.Magma: molten rock that forms in a magma chamber.

Lava: magma that exited the vent.

LANDSCAPING THE CRUSTDefinitions

Faults: fractures in the Earth's crust. They can be normal, reverse and transcurrent.

Normal and reverse faults: they are vertical. Normal faults form when crust moves apart. Reverse

faults form when the crust is compressed.

Horst: a block of rock that has been pushed up by 2 faults.

Rift valleys or Graben: a block of that that has been pushed down by 2 faults.

Transcurrent faults: Horizontal and the movement is in a sideways direction, rock is shattered alongthe fault.

Folding: when continental plates collide rock is under great pressure and it beings to fold without

breaking which creates mountains. Anticline: arch. Syncline: trough. Overfold: fold over fold.

Unconformity: when sediment covers eroded folds.

Shield cones: a way a volcanic mountain is formed, it gets bigger every time it erupts because lava

cools down on its slopes.

Cinder cones: small mountains, created from hot rock and cinders that fell back on the vent it was

expelled from.

Hot spots or plumes: part of a plate that is away from the boundary of a tectonic where magma can

force its way through. Many volcanoes are located directly above these but due to the movement of

tectonic plates they will eventually move on as the hot spot doesn't move with a plate.Composite cones: formed above subduction zones at the edges of tectonic plates.


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# Note

- Magma often cools before it gets to the surface, sometimes in the vent of a dying volcano.Erosion occurs leaving behind a volcanic plug.

- When magma cools below the surface it's called igneous intrusion. There are different typesof igneous intrusion depending on where the magma cools such as dykes, sills, batholiths

and laccoliths.

- Fossil fuels are usually found near plate boundaries. Fossil fuels were originally animalmatter that decomposed to become kerogen, which form other compounds called

hydrocarbons which provides the energy in fuel.

- Ore deposits are found in magma bodies that have solidified.GEOLOGICAL TIME

Definitions

Fossil: evidence of past life found in a rock or other material. This evidence can be remains of

plant/animal or footprints.

Index fossil: fossils that lived over a short period of time and were widespread. They can be used to

date rock and other fossils.

Radioactive dating: comparing the amount of uranium and lead in a rock to find the age of that rock.

Eras: stages in history, made up of periods.

Periods: smaller stages in history.

# Note

- Fossils are created when the remains of an animal/plant are covered by sediments andbecome part of the rock.

- Animals are preserved as shells/skeletons, as moulds, or as quartz, limestone, opal modelsof them. The lower the layer the older fossil

- Era - Period - Epoch, geological measurement of time.- STEPS IN FOMRATION OF FOSSILS:1. an animal dies and it is covered by sediments while under water,2. the soft parts decay and the skeleton is left behind, more sediment covers the skeleton if it

doesn't decay a mould will form or it will be replaced with minerals that seep into the

skeleton,

3. then the layer of sedimentary rock might be pushed up due to movement in the Earth'scrust and weathering and erosion will wear away some of the rock to expose part of the

fossil.


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SEISMOMETER

-- A seismometer records the vibrations from earthquakes- A rotating drum records a line on a sheet of paper. If the earth moves (in this case from left

to right) the whole machine will vibrate too.

- However, the large mass tends to stay still, so the drum shakes beneath the pen, recording asquiggle!

- The confiner prevents the mass from bouncing around all over the place.

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