atomic structure and the periodic table Flashcards

1
Q

What is the average radius of an atom?

A

The average radius of an atom is 0.1 nanometres.

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2
Q

What is the average radius of a nucleus?

A

The average radius of a nucleus is 0.0001 nanometres.

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3
Q

What are the relative masses and charges of sub-atomic particles?

A

sub-atomic particle - relative mas - relative charge

proton - 1 - +1
neutron - 1 - 0
electron - very small (1/1800) - -1

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4
Q

What is a compound?

A

A compound is two or more elements chemically bonded together in fixed proportions. They can only be separated by chemical reactions. They usually have different properties to the elements it’s made from.

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5
Q

What is a molecule?

A

A molecule is any element(s) chemically joined. (eg. O2)

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6
Q

In 2H20, what does the smaller and larger 2’s represent?

A

The larger number represents the molecule number. The smaller number represents the atom number.

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7
Q

What is a mixture?

A

A mixture is two or more elements not chemically bonded together. The properties of each substance is unchanged. They can be separated by physical separation techniques.

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8
Q

What is the chemical formula for ammonia?

A

ammonia - NH3

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9
Q

What is the chemical formula for carbon monoxide?

A

carbon monoxide - CO

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10
Q

What is the chemical formula for calcium chloride?

A

calcium chloride - CaCl2

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11
Q

What is the chemical formula for sodium carbonate?

A

sodium carbonate - Na2CO3

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12
Q

What is the chemical formula for sulfuric acid?

A

sulfuric acid - H2SO4

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13
Q

What is the chemical formula for methane?

A

methane - CH4

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14
Q

What is the chemical formula for nitric acid?

A

nitric acid - HNO3

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15
Q

Before the discovery of the electron, what did people believe the atom was?

A

Before the discovery of the electron, people believed the atom was a tiny sphere that couldn’t be divided.

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16
Q

What did the discovery of the electron lead to? Who came up with this idea?

A

After the discovery of the electron, Thompson came up with the plum pudding model. This is a ball of positive charge with electrons embedded within. There was no nucleus or neutrons.

17
Q

What experiment did Rutherford carry out? What were the three observations and conclusions from this experiment?

A

Rutherford carried out the alpha scattering experiment, where he fired a beam of alpha particles at thin gold foil.

  • most went straight through, so the atom is mostly empty space
  • some were scattered by small angles, so the nucleus is overall a positive charge
  • 1/8000 were sent straight back, so the positive charge is concentrated at the centre
  • therefore, the atom is a positive nucleus surrounded by a cloud of negative electrons
18
Q

What did Niels Bohr suggest?

A

Niels Bohr suggested that electrons orbit the nucleus at different energy levels. He conducted experiments that agreed with this.

19
Q

What did James Chadwick discover?

A

Chadwick discovered the neutron 20 years after the nucleus became an accepted idea.

20
Q

What are isotopes?

A

Isotopes are the same element with the same number of protons but a different number of neutrons.

21
Q

What is the difference between the mass and atomic number?

A

The mass number is the sum of neutrons and protons in an atom. The atomic number is the sum of protons in an atom.

22
Q

What is the relative atomic mass? How do you calculate it?

A

The relative atomic mass is the average mass taking into account different abundances.

sum of (isotope abundance x isotope mass) / 100

23
Q

What do the periods and groups in the periodic table mean?

A

Periods are the rows in the periodic table. They represent the number of electron shells.
Groups are the columns in the periodic table. They represent the number of electrons in the outer shell.

24
Q

What was the order for the early periodic table? Why were they mostly rejected?

A

Scientists attempted to classify the elements by arranging them in order of their atomic weights. The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.

25
Q

How did Mendeleev improve the periodic table?

A

Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered and in some places changed the order based on atomic weights. Elements with properties predicted by Mendeleev were discovered and filled the gaps.

26
Q

What knowledge made it possible to understand why the order of atomic weights wasn’t always correct?

A

Knowledge of isotopes made it possible to explain

why the order based on atomic weights was not always correct.

27
Q

What are some properties across most metals?

A

properties of metals:

  • form + ions
  • strong
  • malleable
  • conductors
  • high boiling and melting points
28
Q

What are some properties across most non-metals?

A

properties of non-metals:

  • form - ions
  • aren’t always solid at room temperature
  • not conductors
  • lower density
29
Q

What is another name for the group 0 elements? What are some of their properties?

A

group 0

  • the noble gases
  • colourless
  • inert
  • very unreactive and don’t easily form molecules due to full outer shell
  • boiling point increases down the table due to greater intermolecular bonds
  • all boiling points are below room temperature
  • reactivity decreases down the group
30
Q

What is another name for the group 1 elements? What are some of their properties?

A

group 1

  • alkali metals
  • soft, low density
  • reactivity increases down the group as the electron is more easily lost due to loss of attraction
  • melting point decreases down the group
31
Q

How does lithium react with oxygen?

A

Lithium reacts rapidly with oxygen to form lithium oxide (Li2O).

32
Q

How does sodium react with oxygen?

A

Sodium reacts very rapidly with oxygen to form sodium oxide (Na2O) and sodium peroxide (Na202).

33
Q

How does potassium react with oxygen?

A

Potassium reacts dangerously rapidly with oxygen to form potassium peroxide (K2O2) and potassium superoxide (KO2).

34
Q

How does group 1 react with chlorine?

A

Group 1 reacts vigorously with chlorine when heated to form white chlorine salts.

35
Q

How does group 1 react with water? Why is it dangerous with potassium?

A

Group 1 reacts vigorously with water to form hydrogen and metal hydroxides, which dissolve in water to form alkaline solutions. Potassium releases enough energy to ignite the hydrogen.

36
Q

What is another name for the group 7 elements? What are some of their properties?

A

group 7

  • the halogens
  • molecules of pairs of atoms
  • radius of atom increases down the group
  • melting point increases down the group
  • reactivity decreases down the group as there is a greater distance from the nucleus and internal electrons shield the nucleus
37
Q

How does group 7 react with non-metals?

A

Group 7 form covalent compounds with non-metals.

38
Q

How does group 7 react with metals?

A

Group 7 forms negative ions with metals and end in -ide.

39
Q

What are some of the properties of the transition metals?

A

transition metals

  • hard and strong
  • high melting point
  • high density
  • much less reactive than group 1
  • can form ions with different charges (Fe2+ or Fe3+)
  • form coloured compounds
  • can be used as catalysts