Atomic Structure Flashcards by Emily Polhill

What are the subatomic particles and their properties?

Proton: Charge +1, Mass 1
Neutron: Charge 0, Mass 1
Electron: Charge -1, Mass ~0

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Where are subatomic particles located?

Protons & Neutrons → Nucleus
Electrons → Orbit in energy levels (shells)

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Why do atoms have no overall charge?

Number of protons = number of electrons, so charges cancel out.

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What is the atomic number?

The number of protons in an atom.

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What is the mass number?

The total number of protons + neutrons.

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How do you calculate the number of neutrons?

Mass number - Atomic number

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What are isotopes?

Atoms of the same element with different numbers of neutrons.

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What is relative atomic mass (Ar) and how is it calculated?

Weighted average mass of isotopes
Ar = (mass × abundance) + (mass × abundance) ÷ 100

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What was Dalton’s atomic theory?

Atoms are tiny, indivisible spheres.

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What did J.J. Thomson discover?

The electron, leading to the ‘plum pudding’ model.

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Describe the Nuclear Model.

A small, dense, positively charged nucleus with electrons orbiting around it in empty space.

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What was concluded from the alpha scattering experiment?

The nuclear model replaced the plum pudding model, showing that atoms have a tiny central nucleus with electrons around it.

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What did Rutherford’s gold foil experiment show?

Atoms have a dense, positive nucleus; most of the atom is empty space.

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What was the method of the alpha scattering experiment?

A beam of alpha particles was fired at thin gold foil, and detectors measured how they passed through or deflected.

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How did Bohr improve the atomic model?

Electrons orbit in fixed energy levels.

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What did Chadwick discover?

The neutron.

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How are electrons arranged in an atom?

In energy levels:
1st shell – 2 electrons
2nd shell – 8 electrons
3rd shell – 8 electrons

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Why do atoms react?

To achieve a full outer shell.

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How are elements arranged in the modern periodic table?

By atomic (proton) number.

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What do groups and periods represent?

Groups = Number of outer electrons.
Periods = Number of electron shells.

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How did Mendeleev arrange the periodic table?

By atomic mass, leaving gaps for undiscovered elements.

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Why did Mendeleev’s table work?

He arranged elements by properties, not just atomic mass.

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Why do non-metals form negative ions?

They gain electrons.

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What do elements in the same group have in common?

Similar chemical properties.

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Where are metals and non-metals found in the periodic table?

Metals: Left & centre Non-metals: Right

Why do metals form positive ions?

They lose electrons.

How do Group 1 metals react with water?

Fizz, move, form an alkaline solution.

Why does reactivity increase down Group 1?

Outer electron is further from the nucleus, weaker attraction, easier to lose.

How do halogens react?

Gain 1 electron to form -1 ions.

Why does reactivity decrease down Group 7?

More electron shells, harder to gain an electron.

What is a displacement reaction?

A more reactive halogen displaces a less reactive one from a compound.

Why are noble gases unreactive?

They have full outer shells.

What happens to boiling points as you go down Group 0?

Increase.

How do transition metals compare to Group 1 metals?

Harder, denser, higher melting points, less reactive.

What are the common properties of transition metals?

Form coloured compounds Multiple ion charges Used as catalysts

What properties does Chromium have compared to Group 1 metals?

Lustrous, brittle, hard metal

What properties does Manganese have compared to Group 1 metals?

Hard and very brittle, difficult to fuse, but easy to oxidise

What properties does Iron have compared to Group 1 metals?

Good conductor, rusts easily in air, strong, ductile, malleable

What properties does Cobalt have compared to Group 1 metals?

Brittle, hard, high melting point

What properties does Nickel have compared to Group 1 metals?

Hard, malleable, and ductile, fairly good conductor of heat and electricity

What properties does Copper have compared to Group 1 metals?

Highly ductile and conductive, malleable, and soft

What are the common ion charges of Chromium?

+2, +3, +4, +5, +6

What are the common ion charges of Manganese?

+2, +3, +4, +5, +6, +7

What are the common ion charges of Iron?

+2, +3, +4, +5, +6

What are the common ion charges of Cobalt?

+2, +3, +4, +5

What are the common ion charges of Nickel?

+2, +3, +4

What are the common ion charges of Copper?

+1, +2, +3

What are the colours of Chromium compounds?

+2 → Blue +3 → Green +6 → Orange

What are the colours of Manganese compounds?

+2 → Pale pink +4 → Brown +6 → Green +7 → Purple

What are the colours of Iron compounds?

+2 → Green +3 → Brown

What are the colours of Cobalt compounds?

+2 → Pink +3 → Blue

What are the colours of Nickel compounds?

+2 → Green

What are the colours of Copper compounds?

+2 → Blue

Which transition metal is used as a catalyst in the decomposition of hydrogen peroxide?

Chromium ## Footnote 2H₂O₂ → 2H₂O + O₂

Which transition metal is used in the Haber Process?

Iron ## Footnote N₂ + 3H₂ ↔ 2NH₃

Which transition metal is used in the manufacture of margarine?

Nickel ## Footnote Adding H₂ to double bonds

What were the key observations of the alpha scattering experiment?

Most particles passed through → Atom is mostly empty space. Some particles deflected → Atom has a small, dense, positive nucleus. A few bounced back → Nucleus is very small but contains most of the atom’s mass.

Describe the Plum Pudding Model.

A sphere of positive charge with negative electrons embedded inside (like raisins in a pudding).

What was the key difference between the Plum Pudding and Nuclear Model?

The Plum Pudding Model suggested no nucleus, whereas the Nuclear Model proved the existence of a small, dense nucleus.

How was the periodic table originally organized?

By atomic mass (not atomic number).

Why did the early periodic table cause problems?

Some elements didn’t fit patterns, as atomic mass doesn’t always match properties.

How did Mendeleev improve the periodic table?

He left gaps for undiscovered elements and arranged them by properties, not just mass.

How many electrons are in the outer shell of Group 1 metals?

1 electron in the outer shell.

How many electrons are in the outer shell of Group 7 (halogens)?

7 electrons in the outer shell.

How many electrons are in the outer shell of Group 0 (noble gases)?

Full outer shell (usually 8 electrons, except helium with 2).

What is produced when alkali metals react with water?

A metal hydroxide and hydrogen gas. ## Footnote Example: Sodium + Water → Sodium Hydroxide + Hydrogen

What is produced when alkali metals react with oxygen?

A metal oxide. ## Footnote Example: Lithium + Oxygen → Lithium Oxide

What is produced when alkali metals react with chlorine?

A metal chloride (salt). ## Footnote Example: Potassium + Chlorine → Potassium Chloride

Does reactivity increase or decrease going down Group 1?

Increases down the group.

Why does reactivity increase down Group 1?

Outer electron is further from the nucleus, so easier to lose.

Does melting and boiling point increase or decrease down Group 1?

Decrease down the group.

Does reactivity increase or decrease going down Group 7?

Decreases down the group.

Why does reactivity decrease down Group 7?

Outer shell is further from nucleus, making it harder to gain an electron.

Does melting and boiling point increase or decrease down Group 7?

Increase down the group.

Does reactivity increase or decrease going down Group 0?

No reactivity (full outer shell).

Does boiling point increase or decrease down Group 0?

Increase down the group.

What happens when lithium reacts with oxygen?

Burns with a red flame, forms lithium oxide.

What happens when sodium reacts with oxygen?

Burns with a yellow flame, forms sodium oxide.

What happens when potassium reacts with oxygen?

Burns with a lilac flame, forms potassium oxide.

What happens when lithium reacts with water?

Fizzes, moves on the surface, slow reaction.

What happens when sodium reacts with water?

Fizzes rapidly, forms a ball, melts due to heat.

What happens when potassium reacts with water?

Ignites with a lilac flame, very rapid reaction.

What happens when lithium reacts with chlorine?

Forms white lithium chloride salt.

What happens when sodium reacts with chlorine?

Forms white sodium chloride salt.

What happens when potassium reacts with chlorine?

Forms white potassium chloride salt.