Science exam revision

metal + acid --> ???

salt + hydrogen

Acid + Base --> ???

salt + water

Acid + Carbonate -> ???

salt + water + carbon dioxide

What is a Bohr shell diagram?

A diagram that shows electrons orbiting around the nucleus of an atom. The capacity of each circle is as follows:
2 in the first shell
8 in the second shell
8 in the third shell
2 in the fourth shell

What type of bonding occurs between two metals and how are the electrons arranged?

Metallic bonding and the electrons are free floating (sea of electrons)

What type of bonding occurs between two non metals and how are the electrons arranged?

Covalent bonding and the electrons are shared.

What type of bonding occurs between a metal and a non-metal and how are the electrons arranged?

Ionic bonding and the electrons are transferred

Ion

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

What is a positive ion called?

cation

What is a negative ion called?

anion

monoatomic ion

an ion made of 1 element e.g., Li+ , S-2

polyatomic ion

an ion made up of more than 1 element e.g., NH4+ , Cr2O7-2

combination/synthesis reaction

a chemical change in which two or more substances react to form a single new substance.
A + B --> AB

decomposition reaction

When something is broken down into smaller molecules (AB→A+B)

combustion reaction

a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light.

What can speed up a reaction?

high temps, large surface area, higher concentration, catalysts.

Characteristics of a base

Produces Hydroxide Ions
Has a pH higher than 8
Turns litmus paper blue
Neutralizes acids
Bitter taste & soapy feel
Bases that are soluble in water are called Alkalis
Concentrated forms are corrosive

What is pH?

a measure of how acidic or basic a solution is.

It is measured by the amount of H+ ions in solution.

Characteristics of acids

An Acid is something that is Soluble
it generally has a sour taste
pH lower than 7.
Acids produce lots of Hydrogen Atoms
neutralize bases.

NH4 (+1 charge)

ammonium ion

NO2 (-1 charge)

nitrite ion

SO3 (-2 charge)

sulfite ion

OH (-1 charge)

hydroxide ion

PO4 (-3 charge)

phosphate ion

CO3 (-2 charge)

carbonate ion

CrO4 (-2 charge)

chromate ion

Cr2O7 (-2 charge)

dichromate ion

MnO4 (-1 charge)

permanganate ion

what does aqueous mean?

the solution is dissolved in water. water is the solvent - it is called aqueous

Soluble

capable of being dissolved

Solvent

A liquid substance capable of dissolving other substances

Why does a catalyst increase the rate of reaction?

This is because they decrease the activation energy needed for a reaction to occur. Catalysts aren't used up in a reaction
examples:
-chemicals
-enzymes

Why does surface area affect the rate of a reaction?

Tiny surface area exposes more of the substance making it easier for the particles to collide

what is an enthalpy diagram

What is an enthalpy diagram?
An enthalpy diagram plots information about a chemical reaction such as the starting energy level, how much energy needs to be added to activate the reaction, and the ending energy.

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Examples:
pesticide resistance in insects, development of antibiotic-resistant bacteria, drug resistant strains of HIV

artificial selection

Breeding organisms with specific traits in order to produce offspring with identical traits.

Examples:
Breeding for different dogs, racehorses bred for strength, corn bred for size

Micro evolution

evolutionary change within a species or small group of organisms, especially over a short period.

Macro evolution

Large scale changes in biological traits resulting in different species

Fossil record

Chronological collection of life's remains in sedimentary rock layers

Fossilisation process

1. Organism dies
2. Organism needs to be preserved
3. Mineralization
4.Erosion removes sediments/rocks above the fossil revealing it.

Types of fossils

1. Indirect fossils
- Not actual organism
- But are remains
- Mold and cast

2. Carbon Film
- organism or plants compressed between different layers
- Organic matter decays
- Leaving a carbon film

3. Replacement
- The original organism's fossil is replaced by minerals

4. Original fossil
- Whole part of the organism has been preserved.
- Skeleton bones, teeth

weathering

The breaking down of rocks and other materials on the Earth's surface.

Relative dating

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock

index fossil

a fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found

fluorine dating

Another relative dating method. It compares the amount of fluorine in different bones found in the same rock. Bones absorb fluorine from the water in the surrounding rock. This happens at a slow rate and depends how much fluorine is in the water surrounding the bone.

Absolute dating

dating methods that give the actual age of rocks and fossils are called absolute dating methods. Absolute dating still gives an estimate, but the estimate is far more specific than estimates provided by relative dating methods. There are many methods of absolute dating, one often used to be radioactive dating.

Radioactive dating

A technique used to determine the actual age of a fossil on the basis of the amount of a radioactive element it contains.

species

A group of similar organisms that can breed and produce fertile offspring.

Speciation

Speciation is the evolutionary process by which native populations evolve to become distinct species.

Hybrid

Offspring of crosses between parents with different traits

Level of classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

(D.K.P.C.O.F.G.S)

adaptive radiation

Adaptive radiation is the rapid diversification of an ancestral population into several ecologically different species, associated with adaptive morphological or physiological divergence.

How does speciation occur?

Variation: There must be variation in the population or speciation cannot occur. This is because natural selection is involved, and selection can only act on variation that is already present in the population.

Isolation: The formation of new species requires isolation. This means different groups of the population are prevented in some way from interbreeding. Isolation prevents gene flow through the population, stopping any differences in one population from reaching the other population.

Selection: Once groups of a population are isolated by barriers, natural selection affects the genotype of each group. This can lead to changes that prevent each group from each other even if they come back together sometime in the future.

What is the order of the planets?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

(M.V.E.M.J.S.U.N)

moon

A celestial body that orbits a planet, is also viewable through sun reflected by the sun

planet

a celestial body moving in an elliptical orbit around a star.

black holes

Formed when massive stars explode in a supernova. The core of the massive star collapses in on itself and keeps on collapsing. They have a gravitational pull so strong that not even light can escape from it.

star

A large, glowing ball of gas held together by its own gravity also generates heat and light through nuclear fusion. Made up of Helium and Hydrogen

galaxy

a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

nebula

a large, diffuse cloud of dust and gas in space

What are the three types of galaxies?

Spiral, Elliptical, and Irregular; The Milky Way is a spiral galaxy

Nuclear Fission

A type of nuclear reaction that is used to release energy from large and unstable atoms by splitting them into smaller atoms

Why is the 'Steady State theory' no longer accepted by scientists?

After the discovery of the cosmological microwave background radiation, which had been predicted as part of the big bang theory but had absolutely no reason to exist within the steady-state theory.

What are 3 theories for the creation of the universe?

1. Big Bang Theory 2. Creation theory 3. Constant State theory

Doppler Effect

an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. When relating to a star, stars change colors depending on how they are moving. If a star is moving away, there would be a slight color change to red (called Redshift) and if a star is moving towards Earth there would be a slight color change to blue (called Blueshift).

Cosmic Background Microwave Radiation

Electromagnetic radiation (leftover from the big bang) comes from every direction and can be detected in all areas of the universe. It is evidence of the big bang

Heliocentric

The sun is the center of the solar system

Geocentric

Earth is the center of the solar system

absolute magnitude

Absolute magnitude is a measure of the luminosity (light) of a celestial object, on an inverse logarithmic astronomical magnitude scale.

spectral type

Spectral type is the temperature of a depending on the colour it emits.

H-R diagram

Hertzsprung-Russell diagram, a graph that shows the relationship between a star's surface temperature and absolute magnitude

Genotype

An organism's genetic makeup, or allele combinations (Ww, RR, cc, FF)

Phenotype

An organism's physical appearance, or visible traits.

Heterozygous

An organism that has two different alleles for a trait (Aa, Bb, Cc)

Homozygous

An organism that has two identical alleles for a trait (aa, bb, cc)

Dominant trait

dominant trait is one that is phenotypically expressed in heterozygotes. A genetic trait is considered dominant if it is expressed in a person who has only one copy of the gene. Dominant traits can't skip a generation.

Recessive trait

a genetic factor that is blocked by the presence of a dominant factor. This trait can skip a generation and Affected children can be born from two unaffected parents.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Nitrogenous bases

adenine, guanine, cytosine, thymine, uracail

Nucleotide

Nitrogenous base + sugar (ribose or deoxyribose) and phosphate group

sugar-phosphate backbone

The alternating chain of sugar and phosphate to which the DNA and RNA nitrogenous bases are attached

DNA

Deoxyribonucleic acid is a complex molecule containing the genetic information that makes up the chromosomes.

Complementary pairing

Adenine = Thymine Cytosine = Guanine

How many chromosomes do humans have?

46 (23 pairs)

Apoptosis

process of programmed cell death

What regulates the cell cycle?

proteins

Mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

What are the stages of mitosis?

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Prophase (poles)

- Chromosomes become visible
- nuclear membrane dissolves
- spindle fibre forms
- Centrioles move to the POLES of the cells

Metaphase (middle)

Chromosomes line up across the middle/center of the cell
Spindle fibres extend and attach to centromeres
Sister chromatids start to be pulled apart

Anaphase (away)

Chromatids move along the spindle fibres away from the middle towards the poles (centrioles)

Telephase (two)

nuclear membrane reforms
Spindle fibres dissolve
We now have 2 sets of chromosomes

Somatic cells

any cell of a living organism other than the reproductive cells.

Why is meiosis necessary?

- For the production of gametes for sexual reproduction
- Genetic variation ( offspring of 2 individuals are different )

The stages of meiosis

Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II

Meiosis

Cell division of cells to form gametes occurs in sex organs.

Prophase I (Meiosis)

Same as prophase in Mitosis
-In meiosis chromosomes pair up to create a homologous pair

Metaphase 1 ( Meiosis )

Same as Metaphase in Mitosis
In meiosis chromosomes line up in homologous pairs

Anaphase 1 (Meiosis)

Same as Mitosis
Instead of chromatids being taken, homologous pair are taken

Telophase 1 (Meiosis)

same as mitosis
Two haploid cells are formed