Atomic Structure and the Periodic Table Flashcards

1
Q

What is an atom?

A

The smallest part of an element that can exist.

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2
Q

What is an element?

A

A substance of only one type of atom.

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3
Q

What is a compound?

A

Two or more elements chemically combined in fixed proportions which can be represented by formulae.

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4
Q

Do compounds have the same properties as their constituent elements?

A

No, they have different properties.

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5
Q

What is a mixture?

A

A mixture has two or more elements or compounds not chemically combined together; It does have the same chemical properties.

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6
Q

What are the methods of Separation (5)

F Cr Sd Fd Chr

A
Filtration
Crystallisation
Simple Distillation
Fractional Distillation
Chromatography
They do not involve chemical reactions.
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7
Q

Describe and explain simple distillation.

A

Simple distillation is used to separate liquid from a solution - The liquid boils off and condenses in the condenser. The thermometer will read the boiling point of the pure liquid. Opposite to evaporation, we keep the liquid.

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8
Q

Describe and explain Crystallisation / Evaporation.

A

Evaporation is a technique of separation of a solid dissolved in a solvent from a solvent. The solution is heated until the solvent evaporates and the solid stays in the vessel.

Crystallisation is similar, but we only remove some solvent by evaporation to form a SATURATED SOLUTION. Then we cool down the solution and the solid starts to crystallise as it becomes LESS SOLUBLE AS LOWER TEMPERATURES.. The crystals can be collected and separated from the solvent via filtration.

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9
Q

Describe and explain fractional distillation.

A

A technique for separation of a mixture of liquids into with different boiling points into fractions.

The mixture is evaporated and its vapours condense at different temperatures in the Fractionating column.

The fractionating column is placed on top of the heated flask and is hot at the bottom and cool at the top. This is so SUBSTANCES WITH HIGH BOILING POINTS CONDENSE AT THE BOTTOM and substances with LOWER BOILING POINTS CONDENSE AT THE TOP.

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10
Q

Describe and explain filtration.

A

Used to separate insoluble solid from a liquid.

The residue gets caught in the filter paper as the particles are too big to fit through the holes in the paper. The FILTRATE comes through the filter paper.

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11
Q

Describe and explain chromatography.

A

Used to separate a mixture of substances dissolved in a solvent.

In paper chromatography, we place paper with a spot containing a mixture in a beaker with a solvent. The bottom of the paper has to be in contact with the solvent.

The solvent level will rise and the spot will separate into few spots with other colours.

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12
Q

Describe the plum pudding model.

A

The atom is a ball of positive charge with negative electron embedded in it.

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13
Q

Describe the Bohr Model and how it come about.

How did the Bohr Model give evidence that lead to a change in the atomic model?

A

The model suggests that electrons orbit the nucleus in forms of shells - formed by alpha scattering experiments.

The results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the nucleus and that the nucleus was charged.

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14
Q

What did James Chadwick discover?

A

The existence of neutrons in the nucleus.

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15
Q

Describe the structure of an atom.

A

Small central nucleus made of protons and neutrons which the nucleus is surrounded by electrons.

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16
Q

State the relative masses and relative charges of the proton, neutron and electron.

A

Proton:
Relative Mass 1
Relative Charge: 1

Neutron:
Relative Mass 1
Relative Charge 0

Electron:
Relative Mass is very small
Relative Charge -1

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17
Q

Explain why atoms are electrically neutral.

A

They have the same number of electrons and protons.

18
Q

What is the radius of an atom?

A

0.1nm

19
Q

Sodium has a Mass Number of 23 and an Atomic Number of 11.

What is Mass Number and Atomic Number?

A

Mass number is the total number of protons and neutrons.

Atomic Number is the total amount of protons.

20
Q

What is an isotope?

A

Atoms of the same proton number but have a different number of neutrons.
They have the same chemical properties as their electronic structure is the same.

21
Q

What are ions?

A

Ions are charged particles.

22
Q

Compare the properties of metals and non-metals.

A

Metals have high boiling and melting point, can conduct heat and electricity, are shiny, are malleable, are very dense, and oxides are basic.

Non-metals have low boiling and melting point, cannot conduct heat or electricity except GRAPHITE, are dull, are brittle, not dense, and oxides are acidic.

23
Q

Horizontal lines of Periodic Tables are … ?

A

Groups

24
Q

Vertical lines of Periodic Tables are … ?

A

Periods

25
Q

Are elements in the same group similiar or different?

A

They may have similar chemical properties, as they have the same number of outer shell electrons.

26
Q

Elements of Group 0 are commonly known as … ?

A

Noble Gases

27
Q

In terms of shells, what is the similarity between elements of the same period?

A

They have the same number of SHELLS.

28
Q

What change in shell number is seen as one moves down a group?

A

The number of shells increases.

29
Q

Early periodic tables were incomplete and elements were placed in inappropriate groups if what was to be followed?

A

The strict order of atomic weights.

30
Q

Knowledge of … made it possible to explain why the order based on atomic weights was not always correct

A

Isotopes

31
Q

Mendeleev overcame some problems with the table by .. ? He changed the order of some elements based on … ?

A
  1. Leaving gaps

2. Atomic Weights

32
Q

State characteristics of Alkali Metals

A
  • One electron in outer shell
  • Low density
  • Are stored under oil to prevent reactions with oxygen
    or air
  • Soft
33
Q

Group 1 Elements + Non-metals = ?

A

Ionic Compounds which are soluble white solids and form colourless solutions - one electron in their outer shell.

34
Q

How do group 1 Elements react with water?

A

Release hydrogen and form hydroxides which dissolve to form alkaline solutions
React vigorously with water fizzing and moving around on surface of water.

35
Q

How does reactivity change moving down Group 1?

A

Increases as atoms get larger, more shells, more distance between nucleus and outer electrons, more easily lose electrons.

36
Q

State characteristics of Group 7 Halogens

A
  • 7 electrons in outer shell
  • Coloured vapours
  • Diatomic molecules
  • From ionic salts with metals
  • Form molecular compounds with non-metals
37
Q

How does reactivity change moving down Group 7 (Halogens) ?

A

Less reactive as less easily gain electrons

38
Q

How does Lithium, Sodium and Potassium react with Water?

A

Lithium floats, fizzes steadily, becomes smaller until it disappears.

Sodium melts to form ball, moves on surface, fizzes rapidly, hydrogen produced makes ORANGE FLAME.

Potassium melts and floats, moves rapidly on surface of water, hydrogen ignites instantly, metal is set on fire and produces LILAC FLAME with small explosion.

39
Q

Write word and balanced chemical equation for the reaction of Potassium with Water.

A

potassium + water → potassium hydroxide + hydrogen

2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)

40
Q

Write word and balanced chemical equation for the reaction of Sodium and Chlrorine.

A

Sodium + chlorine → sodium chloride

2Na(s) + Cl2(g) → 2NaCl(s)

41
Q

Write word and balanced equation for the reaction of Lithium and Oxygen.

A

lithium + oxygen → lithium oxide

4Li(s) + O2(g) → 2Li2O(s)