Propertises and Structures of Matter Flashcards
(21 cards)
What did Dalton’s atomic theory propose?
John Dalton created the first atomic theory:
- Describes matter as tiny spherical particles that are invisible and indestructible
- Atoms cannot be created nor destroyed
- Describes all atoms of a given element are identical
- Elements cannot be broken up into smaller substances and compounds are made up of different elements
What are discrete molecules?
Most non-metallic discrete molecules are small (independent unit), distinct group of atoms held together by strong covalent bonds within the molecule, but separated from other molecules by weak intermolecular forces.
Example of discrete molecules:
Water (H₂O): A simple example of a discrete molecule, where oxygen and hydrogen atoms are bonded together by strong covalent bonds.
But separated to other molecules through weak intermolecular forces.
What are covalent networks/ giant molecules?
Covalent network structures are continuous 3D structures large covalent networks
Forms in a large unit rather than seperate molecules.
Example of Covalent networks:
Carbon likes to form these networks and this is evident in Graphite as it is a giant molecule composed from sheets of carbon bonds.
What is the Definition of Compounds?
A compound is formed when 2 or more different elements are chemically bonded together.
What is the definition of Matter?
Matter can be classified as a pure substance (element or compound) or a mixture.
What is the definition of a Mixture?
Mixtures can be defined as 2 or more pure substances that can be physically separated.
Homogeneous Mixture
A Homogeneous mixture is uniform in composition. E.g milk
Heterogeneous mixture?
A heterogeneous mixture has a composition that varies within the mixture.
What is a solution?
A Solution has one or more solutes that are dissolved in a solvent.
Solvent is a substance in which a solute dissolves in
Solute is a substance that dissolves in a solvent.
What is an Aqueous solution?
It is a solution where the solvent is always water.
Phase transitions : Solid, Liquid, Gas
- melting (solid to liquid)
- solidification (liquid to solid)
- sublimation (solid to gas)
- deposition (gas to solid)
- condensation (gas to liquid)
- vaporization (liquid to gas)
What are fluids?
Both liquids and gases have no fixed shape, and are called fluids.
What is the fluid that passes through the filter is called?
The filtrate
What does it mean when something is volatile?
When a liquid can be easily evaporated. Aka the boiling point of the substance is low.
What is the precipitate?
As the liquid evaporates, the mixture becomes increasingly concentrated, and eventually the solid may precipitate (form and separate) from the solution.
What is crystallisation?
Some solids precipitate as crystals in a process known as crystallisation.
Smaller crystals form when the solvent evaporates quickly, and larger crystals form when the solvent evaporates slowly.
What is a distillation?
If the homogeneous mixture is of two liquids, and one is substantially more volatile than the other, the evaporative process can lead to separation in a process called a distillation.
Formula: Percentage composition by mass of element
Mass of element divided by Mass of compound, times a hundred
What are Alloys?
An alloy is a physical mixture, and the properties of the mixture can be quite different from the properties of the components.
