Properties and Structure of Materials Flashcards
Define nanomaterials.
Substances that contain particles in the size range of 1-100 nm.
They have specific properties relating to the size of these particles which may differ from those of the bulk material.
Define matter.
It has mass and occupies space.
All substances are made up of elements, compounds or mixtures.
Define pure substances.
Homogenous matter with a definite fixed composition.
Examples are both elements and compounds.
5 examples of pure substances.
Fe, N₂, CO₂, HCl, H₂O
Define elements.
Pure substances made entirely of atoms of one element.
Cannot be separated into similar substances by chemical change.
4 examples of elements.
Ne, Al, Br₂, S₈
Define compounds.
Pure substances composed of two or more different elements chemically combined in fixed proportions.
4 examples of compounds.
CO₂, HF, C₆H₁₂O₆, H₂O
Define mixture.
A substance that contained 2 or more pure substances.
Define solution.
Also called homogeneous mixtures.
A mixture of constant bc imposition and properties throughout.
4 examples of solutions.
Air, seawater, stainless steel, smoke
Define heterogeneous mixtures.
Mixtures that have variable composition and properties throughout.
3 examples of heterogeneous mixtures.
Granite, soil, concrete
Define reactants.
Substances that exist before a chemical reaction.
Define products.
Substances formed as a result of a chemical reaction.
Define molecules.
A group of atoms bonded together, forming a small independent group.
Both elements and compounds exist as molecules.
2 examples of molecules.
N₂, CO₂
Define physical properties.
Properties of a substance that can be determined without changing the chemical composition.
3 examples of physical properties.
Boiling point, odour, colour
Define chemical properties.
Properties of a substance that relate to the ability of the substance to form new substances.
3 examples of chemical properties.
Ability to react with water, oxygen or acids
Define boiling point.
The temperature at which the vapour pressure of a liquid is equal to surrounding atmospheric pressure.
Define melting point.
The temperature at which a solid changes state into a liquid
Define hardness.
A measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied.
Define solubility.
The ability of any substance to dissolve in a solvent to form a homogenous solution.
Define conductivity.
A measure of the ability of a substance to conduct an electric current.
Define malleability.
The ability of a material to be beaten into a sheet.
Metals tend to be malleable, other materials tend do be brittle.
Define ductility.
The ability of a material to be drawn in to a wire.
Define lustre.
The ability of a substance to reflect light.
Define density.
The mass per unit volume of a substance.
Equation for density.
Density = mass ÷ volume
⍴ = m ÷ v
Measured in kg/m³ or kg/L
Define chemical change.
Changes in which new substances with different compositions and properties are formed. These are usually irreversible.
2 examples of chemical change.
Hydrogen Peroxide decomposing, burning Propane
Define physical change.
A change only to physical properties, no change is made to the composition of the substance.
2 examples of physical change.
Substances dissolving, substances evaporating
Define filtration and crystallisation
Allows mixtures of an insoluble solid to be separated from a soluble solid
What physical property are filtration and crystallisation based on?
Solubility
How does filtration and crystallisation work?
Mixture added to solvent such as water
Passed through filter paper
Insoluble material retained on filter paper
Soluble material able to pass through
3 examples of filtration and crystallisation.
Separating:
Sugar from sand, mud from water, dust from air
What physical property is distillation based on?
Differences in the boiling points of the different substances.
How does distillation work?
In mixtures of liquids:
Mixture is heated
Liquid with lowest boiling point boils first
Vapour is collected and condensed
2 examples of distillation.
Crude oil being separated into fuels, alcohol being distilled
What physical property is chromatography based on?
The size of the particle or the degree with which the particle is attracted to the stationary phase.
How does chromatography work?
Mixture is passed in a mobile phase through a stationary phase.
Example of chromatography.
Separating inks using water rising up through filter paper.
Define decanting.
Used to separate mixtures of a liquid and an insoluble solid.
How does decanting work?
Liquid is carefully pored from the insoluble sediment at the bottom of the container.
Often separation is incomplete and small amount of solution is left behind in the container.
2 examples of decanting.
Decanting:
Wine from sediment, water from a soil solution
Define materials.
Pure substances with distinct measurable properties or mixtures with properties dependent on the relative amounts of the substances that make up the mixture.
What are chemical bonds caused by?
Electrostatic attractions that arise as a result of the sharing or or transfer between participating ions.