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
