C1 Atomic Structure Flashcards

1
Q

How were atoms described at the start of the 19th century

A

Atoms were described as solid spheres by John Dalton.

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2
Q

How were atoms described by JJ Thomson in 1897

A

Described as Plum Pudding Model

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3
Q

What is the plum pudding model

A

Ball of charge with electrons scattered

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4
Q

What experiment took place in 1909 and what did it tell us about atoms

A

Alpha scattering experiment - mass concentrated at the centre, the nucleus is charged. Most of the mass is in the nucleus. Most atoms are empty space. Nuclear model.

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5
Q

What did Niels Bohr suggest about atoms in 1911

A

Electrons are in shells orbiting the nucleus

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6
Q

What was discovered about atoms in 1940

A

James Chadwick discovered neutrons

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7
Q

Whats the charge, relative mass and location within the atom of protons

A

Charge: +1
Relative Mass: 1
Location: Nucleus

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8
Q

Whats the charge, relative mass and location within the atom of neutrons

A

Charge: 0
Relative Mass: 1
Location: Nucleus

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9
Q

Whats the charge, relative mass and location within the atom of electons

A

Charge: -1
Relative Mass: 1/1850
Location: Outside nucleus in shells

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10
Q

What is the mass number

A

The top number next to an element in the periodic table.

It is the number of protons + number of neutrons

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11
Q

What is the atomic number

A

The bottom number next to an element in the periodic table.

It is the number of protons which is the same as the number of electrons

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12
Q

What is the structure of an atom

A

Atoms are composed of a positively charged nucleus made of protons and neutrons surrounded by negatively charged electrons arranged in shells

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13
Q

Whats an ion

A

An ion is a charged atom (or a group of atoms)

Na+, Cl- Charged atoms

SO4^2- Charged group of atoms

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14
Q

Why are some ions positive and some negative

A

Atoms that gain electrons form negative ions. If atoms lose electrons form positive ions.

Oxygen atom: 8p 8n 8e: O
Oxygen ion: 8p 8n 10e: O^2-

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15
Q

What are isotopes

A

Isotopes are atoms of the same element with different numbers of neutrons. They have identical chemical properties, but their physical properties, such as density, can differ.

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16
Q

What is the electronic structure of atoms

A

The 1st electronic shell can hold max. 2 electrons
2nd shell 8
3rd shell 8
4th shell Holds the remainder

17
Q

What does the number of electrons in the outer shell determine

A

Which group the element is in and determines in which way the element reacts (it’s reactivity).

18
Q

What is the overall charge of an atom

A

0

Same number of protons as electrons

19
Q

How many times bigger is the radius of an atom compared to the radius of the nucleus

A

The radius of an atom is around 10,000 times the size of the radius of the nucleus

20
Q

Do compounds always have similar properties to the elements that make it up

A

No. Compounds often have totally different properties to the original elements

21
Q

Which side of the chemical equation are reactants found

A

The left

22
Q

What is a compound

A

A compound is a substance formed from two or more different elements in fixed proportions, held together by chemical bonds.

23
Q

What type of process is needed to separate a compound into it’s elements

A

A chemical reaction

24
Q

What is a mixture

A

A mixture consists of two or more elements or compounds that are combined, but not chemically bonded together

25
Q

Why are techniques to separate mixtures described as physical processes

A

The separation of a mixture is a physical process because it does not involve any chemical reactions, and no new substances are made.

26
Q

When substances are combined in a mixture, do their chemical properties change.

A

No. The chemical properties of the substances in a mixture are unchanged

27
Q

How does filtration work

A

Filtration works by passing the mixture through a filter. The liquid passes straight through, but the insoluable solid particles are caught by the filter.

28
Q

Why might crystallisation be used instead of evaporation

A

Crystallisation is used if the salt will decompose when heated, or if you want to make big crystals of the salt.

29
Q

When can filtration be used to separate a mixture

A

Filtration can be used when you have a mixture of an insoluble solid and a liquid.

30
Q

When is crystallisation used to separate a mixture

A

Crystallisation is used to separate a soluable solid from a solution

31
Q

Why can’t simple distillation be used to separate substances with similar boiling points.

A

If the boiling points of the compounds are too close together, they will all evaporate and mix together again.

32
Q

What is the tube in distillation called and what is it used for

A

Condenser. It cools the vapour and turns it back to liquid, so it can be collected. The cooling water enters at the bottom and exits at the top because when the water heats up it rises and exits at the top.

33
Q

Three liquids with boiling points of 81°C, 49°C and 56°C. How could you use fractional distillation to separate a mixture of these compounds

A

Heat the gractioning column to 49 to 55 degress so only one liquid evaporates and then condenses to be collected in a flask. Then increase the temperature to 56 to 80 degrees so another liquid evaporates and condenses to be collected in another flask, therefore leaving the final liquid behind.

34
Q

How can paper chromatography be used to separate a mixture containing three different dyes.

A

Put a dot of the dye mixture on the pencil line and place the filter paper in solvent. The solvent should be below the pencil line. Each different dye in the mixture will move up the paper at a different rate, seperating out the dyes. You’ll end up with three seperate spots on your chromatogram.

35
Q

Why can’t you use a pen to draw a line near the bottom of the filter paper.

A

It should be drawn in pencil because the pen contains ink which will dissolve in the solvent