Topic 1 - Atomic Structure And The Periodic Table Flashcards
Which elements are subscripted by a 2?
Iodine, bromine, chlorine, fluorine, oxygen, nitrogen, hydrogen.
What is a compound?
A substance that contains two or more elements that are chemically combined.
What happens in a chemical reaction?
One or more new substances are formed.
For every carbon atom how many oxygen atoms are there?
2.
What is an ion?
A charged particle formed when an atom, or a group of atoms, loses or gains electrons.
What are reactants?
Substances that react together in a chemical reaction.
What is the symbol for solid?
(s)
What is the symbol for liquid?
(l)
What is the symbol for gas?
(g)
What is the symbol for aqueous solution?
(aq)
What happens when a substance dissolves in water?
An aqueous solution forms.
What is the law of conservation of mass?
No atoms are lost or made during a chemical reaction, so the total mass of the products is equal to the total mass of the reactions.
What does a pure substance consist of?
One element or one compound.
What does a mixture consist of?
Two or more different substances, not chemically joined together.
Explain separating mixtures?
They can be separated by physical processes, these processes do not involve chemical reactions and no new substances are made.
What is filtration and an example of it?
Used to separate an insoluble solid from a liquid. For example, sand and water.
Why is filter paper used in filtration?
It has tiny holes in it that are large enough to let small molecules and dissolved ions through.
What is the method for filtration?
One beaker contains a mixture of solid and liquid, the other contains a funnel with filter paper
The solid and liquid mixture is poured into the filter funnel.
Image caption,
2. The solid and liquid mixture is poured into the filter funnel
The liquid drips through the filter paper into the beaker below, but the solid particles are caught in the filter paper.
Image caption,
3. The liquid drips through the filter paper but the solid particles are caught in the filter paper
What is crystallisation used for and what is an example of this?
Used to produce solid crystals from a solution. For example, it is used to obtain copper sulfate crystals from copper sulfate solution.
What is the method for crystallisation?
- A solution is placed in an evaporating basin and heated with a Bunsen burner.
The amount of the solution has reduced as some has evaporated. Small particles can be seen at the bottom of the basin containing the solution
Image caption, - The volume of the solution has decreased because some of the water has evaporated. Solid particles begin to form in the basin.
The solution has evaporated, leaving a crystalised solute
Image caption, - All the water has evaporated, leaving solid crystals behind.
What is simple distillation and an example of this?
Used to separate a solvent from a solution. For example, producing pure water from seawater.
Why does simple distillation work?
because the dissolved solute has a much higher boiling point than the solvent. When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and
condensed. The remaining solution becomes more concentrated as the amount of solvent in it decreases.
What is the method for simple distillation?
- Salty water is heated
- The water vapour cools in the condenser and drips into a beaker
- The water has condensed and is now in the beaker, the salt stays behind
What is fractional distillation and what is an example?
Used to separate different liquids from a mixture of liquids. For example, separating ethanol from a mixture of ethanol and water.
Why does fractional distillation work?
because the different liquids have different boiling points. When the mixture is heated:
vapours rise through a column which is hot at the bottom, and cooler at the top
vapours condense when they reach a part of the column that is below the temperature of their boiling point
each liquid is led away from the column
What is the method for fractional distillation?
(Ethanol and water)
- Water and ethanol solution is heated
- The ethanol evaporates first, cools, then condenses
- The water left evaporates, cools, then condenses
What is paper chromatography and what is an example?
Used to separate mixtures of soluble substances. For example, coloured substances - food colourings, inks, dyes, or plant pigments.
What is the method for paper chromatography?
- Ink or plant dye is dotted along the pencil line.
- As the paper is lowered into the solvent, some of the dye spreads up the paper
- The paper has absorbed the solvent, and the dye has spread further up the paper
What are the two phases that chromatography relies on?
The stationary phase- very uniform, absorbent paper.
The mobile phase- the solvent that moves through the paper, carrying different substances with it.
What happens when a mixture is heated in simple distillation?
The solvent evaporates and leaves the solution.
What method is used to obtain pure water from salt solution?
Simple distillation.
Who published his ideas about atoms in 1803 and what were they?
John Dalton. He thought that all matter was made of tiny particles called atoms.
Who discovered the electron?
Jj Thomson.
Which model of the atom did jj Thomson suggest?
The plum pudding model.
What was the plum pudding model?
A ball of positive charge with negative electrons embedded in it.
In 1909, who designed the alpha particle scattering experiment?
Ernest Rutherford.
What was the alpha particle scattering experiment?
It was designed to test the plum pudding model. Positively charged alpha particles were fired at thin gold foil, most went straight through but a few were scattered in different directions.
What new model of the atom was suggested after the evidence from the alpha particle scattering experiment and who suggested it?
The nuclear model and Ernest Rutherford.
In the nuclear model. . ?
The mass of the atom is concentrated at its centre, the nucleus
The nucleus is positively charged.
Who developed the nuclear model?
Niels Bohr.
Further experiments by Niels Bohr led to what?
The idea that the nucleus contained small particles called protons.