Chapter 2: The nature of matter Flashcards
Why do we get three different states of matter?
Because of the different forces of attraction. When atoms overcome forces they can then change state. These forces affect the melting and boiling point of a substance.
What does a pure substances melting and boiling point depend on?
The atmospheric pressure and forces between the substance .
What is sublimation and give two examples?
When a substance goes straight from the solid state to the gaseous state skipping the liquid state.
Eg. dry ice and solid iodine.
What is deposition and give an example?
When a substance goes straight from the gas state to the solid state skipping the liquid state.
Eg. frost on cold mornings
What does the kinetic model of matter state?
That matter consists of a large number of small particles that are in a continuous random movement. The nature and amount of motion differs in solids, liquids and gases.
What happens to the temperature of a substance while a change of state is taking place?
energy is being absorbed and given out and so the temperature stays constant during the phases of changing state.
How can you indicate the degree of purity of a substance?
By the sharpness of its melting and boiling points.
What are some methods that you can use to purify a substance from a mixture?
filtration, distillation, and chromatography
What is a mixture?
It’s a combination of 2 or more types of atoms so no chemical bonds.
What is the importance of purity?
- quality control for medicines
- quality control for raw materials
- confirm composition of finish products
Define volatile:
Something that evaporates easily and has a relatively low boiling point.
Define viscosity:
the resistance to flow
What is filtration?
a physical technique to separate solids from fluids by adding a medium through which only fluids can pass.
What does it mean if a substance is insoluble?
it doesn’t dissolve
How does the words solution, solute and solvent relate to each other?
A solution is a mixture of a solute (the dissolved substance) and the solvent (the substance that the solute dissolves in)
What does it mean if a solution is saturated?
It means that the solute can’t dissolve in the substance any more.
Solution only contains single bonds.
What is crystallization?
When you take a solution and evaporate it and leave behind the solute as crystals.
What is an element?
a substance that can’t be chemically broken down into simpler substances.
What is a compound?
A pure substance made from two or more elements chemically combined together. The properties of compounds differ from the elements that they are made of.
What are atoms?
They are the basic building blocks of life that cannot be changed but just reshuffled in chemical reactions.
They combine in fixed ratios to form elements and molecules.
What is a molecule?
Atoms of different elements combine to make molecules of a compound.
What is the subatomic particles of an atom and what are their relative charges?
Electron- negative electrical charge (-1) and hardly any mass.
Proton- one positive charge (+1) and a mass of one unit.
Neutron- no electrical charge (0) and a mass of one unit.
What is the structure of the subatomic particles of an atom?
The protons and neutrons are bound together in the nucleus and make up most of the mass.
The electrons ‘orbit’ the nucleus in different energy levels or shells.
What is an isotope?
atoms of the same element which have the same proton number but a different nucleon number
What is the atomic number of an element?
The number of protons in that element and then in turn the number of electrons in that element.
What is the mass number of an element?
it’s the total number of protons and neutrons in an atom.
What is a radioisotope?
When there is an imbalance of neutrons and protons and in the nuclei that causes them to be unstable so the nuclei break up spontaneously, emitting radiation.
What are some industrial uses of radioisotopes?
-isotope of uranium used in nuclear power stations
-monitoring of the levels of filling in containers
-checking the thickness of plastic, paper or metal foil during continuous production
What are some medicinal uses of radioisotopes?
-cancer tumors can be killed using radioisotopes
- helps to sterilize medicinal instruments
What is the maximum number of electrons in each energy level?
1st level: 2 electrons
2nd level: 8 electrons
3rd level: 8 electrons
