Science Exam

What is a literature review

reading older literature, the current knowledge, identifying trends, gaps, and relationships in the literature.

What are the scientific method steps

plan - identify problems - formulate research questions, conduct- carry out exp - observe - record, process - explaining trends patterns - analyses data, evaluate - find problems in relation to questions or hypothesis

What is IMRAD and what are the steps

IMRAD stands for Introduction, Methods, Results, and Discussion; it is a structured format for presenting research papers, where each section serves a specific purpose in conveying the research process and findings.

how is the periodic table organised

The periodic table is organized by increasing atomic number, with elements grouped into rows (periods) and columns (groups) based on their similar chemical properties.

what does hydrophobic mean

Hydrophobic refers to the property of a substance to repel water or fail to mix with water.

What factors affect the rate of reaction

Factors that affect the rate of reaction include temperature, concentration of reactants, surface area, and the presence of catalysts.

what is mode, median, mean and range

Mode is the value that appears most frequently, median is the middle value when data is ordered, mean is the average of the values, and range is the difference between the highest and lowest values in a data set.

what is the formula for density

Density is calculated by dividing mass by volume, expressed as d- mass/volume

what is microscope resolution

Microscope resolution refers to the ability of a microscope to distinguish between two points or details in a specimen.

what is magnification in a microscope

Magnification in a microscope is the process of enlarging the appearance of an object to allow for detailed observation of its features.

what is mass

the measure of how much matter is in a substance

what is volume

the amount of space something takes up

what are hints of chemical reactions/properties

burning, rusting, reacts quickly or slowly to chemicals and oxygen combustion (explosion)

what is an exothermic change

a type of change that releases energy, usually in the form of heat or light, during a chemical reaction.

what is an edothermic change

a type of change that absorbs energy, typically in the form of heat, during a chemical reaction.

what does suspension mean

when one substance does not dissolve and separates when the mixture is allowed to stand because the particles are larger in those solutions

when mixed and spread out, this is called a dispersion.

solid suspended (sand in water)

solid suspended in a agas (sand carried by the wind)

liquids suspended in another liquid (medicines in liquid)

what is a colloid

a substance consisting of particles substantially larger than atoms or ordinary molecules but too small to be visible to the unaided eye

Tynell Effect shows this

Emulsions

common type of colloid is an emulsion. Its a mixture of a liquid where one liquid will not dissolve another (mayo)

emusions are a form of colloids

ways to separete an INSOLUBLE substance

gravity separation - heavy particles sink

decanting - the process of separation of liquid from solid and other immiscible (non-mixing) liquids, by removing the liquid layer at the top from the layer of solid or liquid below. The process can be carried out by tilting the mixture after pouring out the top layer.

sieving - instrument used to separate coarse from fine parts of loose matter

filtration - separates solids from gases, solids from liquids, liquids from gases and liquids from other liquids

magnetic separation - separates magnetic materials passed through a large drum

centrifuging - rotates at a high speed, forcing substances with different densities to separate (blood)

Ways to separate SOLUBLE substances

• Chromatography - a process that separates a mixture by making it move through another substance like a paper strip. Works because all the chemicals in the mixture are attracted to the solid material by different amounts

• Evaporation - process using heat to make a liquid solvent change state to a gas, leaving the solute behind

• Distillation - process that uses evaporation and condensation to separate solids from liquids or liquids from liquids

• Adsorption - the method of separation where particles of liquid, solid or gas stick to the outside of a solid

• Purifying water -

What is the tynall effect

scattering of a beam of light by a medium containing small suspended particles—e.g., smoke or dust in a room, which makes visible a light beam entering a window.

What is density

density measures how much matter is packed into a certain space and is one of the physical properties of a substance

• how heavy an amount of a substance will be

• whether the substance will sink or float

Comparing density

density is reffered to in g/cm squared

density can change at different temperatures and when a substance changes state

density is defined as the mass of an object divided by its volume

• example: hot air is less dense than cool air

• water has a density of 1.0g/cm squared, oil floats because its less dense

physical and chemical changes examples

physical

• crushing an aluminium can

• ice melting

• mixing liquids together

chemical

• a new substance is created

• ripening of apples to turn red

• leaves changing colour in autumn

while drawing a graph, identify the independent variable, dependant variable and what a control variable is

the independent variable is the variable that changes

the dependant is the variable that is being measured

what is an acid

A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals

and example of an acid are the enzymes that break food down in your stomach

What are traits of acids

• sour taste

• low pH

• reacts with metals

• can be neutralised by bases that produce water and salt

strengths and weaknesses of acids

• the strength of an acid depends on how many hydrogen ions are released

• strong acids are hydrochloric acids, sulphuric acids and nitric acid

• weak acids release few hydrogen ions, like citric acid, lactic acid, ascorbic acid (vitamin c)

• acids can be concentrated or diluted (concentrate - little water, diluted - lots of water

what are bases and alkali

a base is a substance that releases hydroxide ions in an aqua solution or something that can accept a hydrogen ion

when a base is dissolved into water it is called an alkali/ alkaline solution

strong and weak bases traits

strong bases release alot of hydroxide ions (calcium hydroxide, sodium hydroxide)

weak bases release only a few hydroxide ions (hydrogen carbonate or baking soda and magnesium)

what are the chemical properties of bases

caustic, soapy, bitter taste, conducts electricity, neutralised by acids

what is pH (how to measure pH add)

the concentration of hydrogen ions in a solution, measured using the pH scale

Elephants toothpaste and magic sand experiment

what is chromatography

chromatography is a laboratory technique for the separation of a mixture into its components. we used it to separate and find differing ink samples

whats a monotomic element

an element that exists as a single atom (Helium,Neon)

What is a molecular element

the same type of atom bonded together in groups or molecules

iodine

What is a compound

a substance formed when two or more chemical elements are chemically bonded together

what are the two types of bonding created from compounded substances

covalent bonds

• in a state of liquid/gas

• occurs between two non metals

• low boiling point

ionic bonds

• in a solid state

• metal element and a non metal element

• high boiling points

In ionic bonding, one atom donates electrons to the other. In covalent bonding, the two atoms share electrons

What are four types of mixtures

solutions, suspensions, colloids and solids

how is magnification calculated

eye lens x objective lens

what did the experiments done in LAB show us, how does it connect to the exam?

magic sand - showed what hydrophobia in a substance looks like, repelled and did not mix with water

elephants toothpaste - showed what the use of a catalyst can do in a chemical reaction (potassium iodide)

slime - this displayed emulsion between the PVA glue and water

what are the two electron microscopes called, and outline the differences

TEM Transmission electron microscopes (TEM)

• specimen must be cut into thin slices

• electrons pass through the specimen

• able to get an inner view of the structure of specimen (cell)

Scanning electron microscopes (SEM)

• No need to slice the specimen

• The electrons reflect off

• extremely magnified view of specimen