Atomic Structure and the Periodic Table Flashcards
Atom
Smallest part of an element that can exist
Element
A substance that contains only one type of atom
Compounds [3]
- Contains two or more different types of atoms
- Which are chemically combined
- In fixed proportions
Mixtures [2]
- Contains two or more elements or compounds
2. Which are NOT chemically combined
What are the two parts of an equation?
- Reactants
2. Products
Describe the law of conservation of mass [3]
- Total mass of products = Total mass of reactants
2. As no atoms are lost or made
What are the two ways in which components of compounds can be separated?
- Electrolysis
2. Chemical reactions
What are the characteristics of the components of a mixture?
They retain their original characteristics
What is filtration used to separate?
Soluble solids/ (dissolved to liquids) from insoluble solids
Describe the process of filtration [4]
- Place a filter paper into a funnel
- Pour the liquid through the paper
- The solid cannot pass through the paper and so remains
- The liquid passes into a beaker
What is crystallisation used to separate?
A soluble solid from a solution
Describe the process of crystallisation [3]
- GENTLY HEAT the solution in an evaporating disk using a burner
- Once Crystals begin to form, LEAVE TO COOL
- After the solution has turned into crystals, DRY and FILTER remaining liquid
What are the 2 ways to dry crystals?
- Pat with filter paper
2. Using a warm oven
What does simple distillation separate?
A solvent from a solution
Describe the process of removing salt from water using simple distillation [3]
- Salty water is HEATED
- Water vapour COOLS in a condenser and drips into a beaker
- Water has condensed and salt remains
What does fractional distillation separate?
Mixtures in which the components have different boiling points
Describe the process of separating a mixture using Fractional Distillation [3]
- Vapour RISES through column which is hot at bottom and cool at top
- Vapours CONDENSE at section with temperature lower than their boiling point
- Liquids led away from column
What is chromatography used to separate?
To separate mixtures of coloured soluble components
What is the indicator that a substance is pure on a chromatogram?
Produces one spot
What is the indicator that a substance is impure on a chromatogram?
Produces two or more spots
What is the formula for the Rf value?
Distance travelled by adults/ Distance travelled by solvent
Who created the Plum pudding model of the atom?
Thompson
Describe the Plum Pudding model of the atom [2]
- Atoms contained tiny, negative electrons
2. Surrounded by a sea of positive charge