Science exam Flashcards
The substances at the end of a chemical reaction are:
Products
The word equation for rust is:
Iron + water + oxygen
What is a chemical change?
A chemical change cannot be reversed, the bonds between atoms or molecules are altered to create a new substance
What is a physical change?
A physical change can be reversed
List four types of physical change
- Shape
- Colour
- Odour
- Feeling
Example of a physical change
Ice cream melting
Example of a chemical change
Hydrogen and oxygen mixing to form water
List two ways of protecting iron against rust:
- Galvanising
2. Prevent oxygen or moisture from contacting the metal
List three ways of speeding up a chemical reaction
- Increase surface area
- Increase the amount of reactant
- Increase the concentration
List four observations that provide evidence of a chemical change
- Colour change
- Precipitation
- Temperature change
- Light is emitted/ flames are seen
What is galvanising?
Galvanising is to coat a metal in a layer of zinc.
The word atom comes from the Greek word:
Atomos, meaning that which cannot be divided
An element is a substance that:
Cannot be broken down into other substances
The period an atom belongs to is also the number of:
Electron shells an atom has
What is a compound?
A compound is a substance that is a combination of two or more elements
Sea water is an example of:
A mixture
What is a metalloid?
A metalloid has features of both metals and non- metals
What are the features of metal?
The features of metal are: They are solid at room temp They can be polished to be shiny They are good electricity and heat conductors They are malleable They can be made into a wire They usually melt at high temperatures
What are the features of non-metals?
They cannot be polished to look shiny They are brittle They cannot be bent into a shape Usually poor conductors of heat Melt at low temperatures
How many non- metals are there?
22
What are the eight metalloids?
Boron Silicon Arsenic Germanium Antimony Polonium Astatine Tellurium
What is a mixture?
Mixtures can be made up of two or more elements, two or more compounds or a combination of them both.
How do you find the mass number
It is the sum of the protons and neutrons
How do you find the number of neutrons?
Mass number - atomic number = number of neutrons
What are the features of a solid ?
Solids have a definite shape
They take up a fixed amount of space
Can’t be compressed
Cannot be poured
What are the features of liquids?
Takes up the space of the container it is in
Take up a fixed amount of space
It flows
Cannot be compressed
What are the features of gases?
Gases spread out
Will not stay in a container without a lid
Gases take up all available space (diffusion)
Can be compressed
What are fluids?
Fluids are all liquids and gases as they can flow or spread
What is the change from liquid to gas known as?
Evaporation
What is the change from solid to liquid know as?
Melting
What is the change from gas to liquid known as?
Condensation
What is the change from liquid to solid know as?
Freezing
What is the change from solids to gases know as?
Sublimation
What happens to particles when the temperature increases?
The particles move faster
Clouds are formed when:
Water evaporates
What is the core body temperature of a healthy human?
37 degrees Celsius
The substances at the beginning of a reaction are:
Reactants
