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Chemistry 🧪 > Basic ideas about atoms > Flashcards

Basic ideas about atoms Flashcards

1
Q

What is the atomic number?

A

The number of protons in the nucleus of an atom.

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2
Q

What is the mass number?

A

The number of protons and neutrons in the nucleus of an atom.

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3
Q

What are isotopes?

A

Atoms with the same number of protons but a different number of neutrons.

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4
Q

How are positive ions (cations) formed?

A

When an atom loses one or more electrons.

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5
Q

How are negative ions (anions) formed?

A

When an atom gains one or more electrons.

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6
Q

What is alpha radiation and its properties?

A

A helium nucleus, least penetrating (stopped by air), most ionising.

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7
Q

What is beta radiation and its properties?

A

High energy electron, stopped by a thin layer of metal.

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8
Q

What is positron radiation and its properties?

A

Anti electron, stopped by a thin layer of metal.

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9
Q

What is gamma radiation and its properties?

A

Electromagnetic wave, most penetrating (stopped by lead), least ionising.

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10
Q

What is the half life?

A

The time taken for half the atoms in a radioisotope to decay.

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11
Q

When an element emits alpha radiation, what happens to its mass and atomic number?

A

Its mass number decreases by 4 and its atomic number decreases by 2.

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12
Q

When an element emits beta radiation, what happens to its mass and atomic number?

A

Its mass number is unchanged and its atomic number increases by 1.

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13
Q

When an element emits positron radiation, what happens to its mass and atomic number?

A

Its mass number is unchanged and its atomic number decreases by 1.

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14
Q

What are the dangers of high energy radioactive emission?

A

They break chemical bonds in cell molecules, giving rise to changes in DNA which can cause mutations and the formation of cancerous cells at low doses, and cell death at high doses.

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15
Q

What are some beneficial uses to radioactivity?

A

In Medicine: Colbalt-60 used in radiotherapy to treat cancer
In Radio-dating: Carbon-14 used to calculate the age of plant and animal remains
In Analysis: Monitoring the thickness of foil

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16
Q

What shape is the S orbital?

A

Spherical and contains up to two electrons.

17
Q

What shape is the P orbital?

A

Dumbbell and contains up to six electrons.

18
Q

What shape is the D orbital?

A

Dumbbell with a ring and contains up to ten electrons.

19
Q

What is electron configuration?

A

The arrangements of electrons in an atom.

20
Q

What is electron shielding?

A

The repulsion between electrons in different shells. Inner shell electrons repel outer shell electrons.

21
Q

Nuclear attraction depends on what factors?

A

Nuclear charge
Electron shielding
Distance of the outer electron to the nucleus

22
Q

What is the first molar ionisation energy?

A

The energy to remove one mole of electrons from one mole of gaseous ions to form one mole of 1+ gaseous ions.

23
Q

Why do successive ionisation energies always increase?

A

There is a greater nuclear charge as the same number of protons are holding fewer electrons
As each electron is removed there is less repulsion and each shell is drawn slightly closer to the nucleus
As the distance of each electron from the nucleus decreases, the nuclear attraction increases

24
Q

Describe the steps of the emission spectrum

A

*Electron absorbs energy and jumps to higher level
*Electron is excited and drops to a lower energy level
*Emits a photon in the visible region corresponding to the gap in energy levels

25
Q

What is in the Paschen series?

A

Infrared light (n=3).

26
Q

What is in the Balmer series?

A

Visible light (n=2).

27
Q

What is in the Lyman series?

A

Ultraviolet light (n=1).

28
Q

What is the convergence limit?

A

When the spectral lines become so close together they have a continuous band of radiation and separate lines can’t be distinguished.

29
Q

Describe the steps of the absorption spectrum

A

When white light is passed through the vapour of an element, certain wavelengths will be absorbed by the atoms, and removed from the light. The wavelength of the lines correspond to the energy taken in by the atoms to promote electrons from lower to higher energy levels.

30
Q

How to find energy?

A

Energy= plancks constant x speed of light/ wavelength

31
Q

What is the emission spectrum for a hydrogen atom?

A

A line upwards from n=1 to n=infinity.

32
Q

State the regions of light in the emission spectrum in increasing energies

A

Infrared -> Visible -> Ultraviolet

33
Q

How can you use the emission spectrum to calculate ionisation energy?

A

By measuring the wavelength at the convergence limit and using E=hf or E=hc/wavelength to calculate energy.

34
Q

What are there several series of lines?

A

Each line corresponds to electron falling to different energy levels.

35
Q

Why do the lines of each series converge?

A

As energy levels get closer together.

Chemistry 🧪 (15 decks)

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