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OCR A LEVEL CHEMISTRY > 2.1.1 - Atomic Structure and Isotopes and 2.1.2. Compounds, formulas and equations > Flashcards

2.1.1 - Atomic Structure and Isotopes and 2.1.2. Compounds, formulas and equations Flashcards

1
Q

What was stated in Dalton’s atomic theory? (4)

A
  • Atoms are tiny particles made of elements
  • Atoms cannot be divided
  • All the atoms in an element are the same
  • Atoms of one element are different to those of other elements
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2
Q

What did Thompson discover about electrons? (3)

A
  • They have a negative charge
  • They can be deflected by magnet and electric field
  • They have very small mass
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3
Q

Explain the plum pudding model

A

Atoms are made up of negative electrons moving around in a sea of positive charge

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4
Q

What were Rutherford’s proposal after the gold lea experiment? (4)

A
  • Most of the mass and positive charge of the atom are in the nucleus
  • Electrons orbit the nucleus
  • Most of atom’s volume is the space between the nucleus and the electrons
  • Overall positive and negative charges must balance
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5
Q

Explain the current model of the atom

A
  • Protons and neutrons are found in the nucleus
  • Electrons orbit in shells
  • Nucleus is tiny compared to the total volume of atom
  • Mot of atom’s mass is in the nucleus
  • Most of the atom is empty space between the nucleus and the electrons
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6
Q

What is the charge of a proton?

A

1+

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7
Q

What is the charge of an electron?

A

1-

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8
Q

Which particle has the same mass as a proton?

A

Neutron

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9
Q

Which two particles make up most of atom’s mass?

A

Protons and neutrons

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10
Q

Which letter is used to represent the atomic number of an atom?

A

Z

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11
Q

What does the atomic number tell about an element?

A

Atomic number = number of protons in an atom

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12
Q

Which letter represents the mass number?

A

A

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13
Q

How is the mass number calculated?

A

Mass number = number of protons + number of neutrons

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14
Q

How to calculate the number of neutrons?

A

Number of neutrons = mass number - atomic number

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15
Q

Define isotope

A

Atoms of the same element with different number of neutrons and therefore has a different mass

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16
Q

Why does different isotopes of the same element react in the same way? (2)

A
  • Neutrons have no impact on the chemical reactivity

- Reactions involve electrons, isotopes have the same number of electrons in the same arrangement

17
Q

What are ions?

A

Charged particles that is formed when an atom loses or gains electrons

18
Q

What is the charge of the ion when electrons are gained?

A

Negative

19
Q

What is the unit used to measure atomic masses called?

A

Unified atomic mass unit, u

20
Q

Define relative atomic mass

A

The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of carbon-12

21
Q

What is the unit of relative atomic mass?

A

no units

22
Q

Define relative isotopic mass

A

The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon-12

23
Q

The relative isotopic mass is same as which number?

A

Mass number

24
Q

What two assumptions are made when calculating mass number?

A
  1. Contribution of the electron is neglected

2. Mass of both proton and neutron is taken as 1.0 u

25
Q

How to calculate the relative molecular mass and relative formula mass?

A

Both can be calculated by adding the relative atomic masses of each of the atoms making up the molecule or the formula

26
Q

What are the uses of mass spectrometry? (3)

A
  • Identify un known compounds
  • Find relative abundance of each isotope of an element
  • Determine structural information
27
Q

How does a mass spectrometer work?

A
  • The sample is made into positive ions
  • They pass through the apparatus and are separated according to mass to charge ratio
  • A computer analyses the data and produces a mass spectrum
28
Q

How is the group number related to the number of electrons?

A

Group number = number of electrons in the outer shell

29
Q

Does the group number indicate the horizontal or vertical column in the periodic table?

A

Vertical column

30
Q

Do metals usually gain or lose electrons?

A

Lose electrons

31
Q

Which are the 4 elements that don’t tend to form ions and why?

A

The elements are beryllium, boron, carbon and silicon

Requires a lot of energy to transfer outer shell electrons

32
Q

What are molecular ions?

A

Covalently bonded atoms that lose or gain electrons

33
Q

What is the charge of an ammonium ion?

A

+1

NH4 +

34
Q

What is the charge of a hydroxide ion?

A

-1

OH-

35
Q

What is the charge of a nitrate ion?

A

-1

NO3 -

36
Q

What is the charge of a carbonate ion?

A

-2

CO3 ^2-

37
Q

What is the charge of a sulfate ion?

A

-2

SO4 ^2-

38
Q

What is an empirical formula?

A

Simplest whole number ratio of atoms of each element present in a compound

39
Q

How to calculate empirical formula?

A
  • Divide the amount of each element by its molar mass
  • Divide the answers by the smallest value obtained
  • If there is a decimal, divide by a suitable number to make it into a whole number

OCR A LEVEL CHEMISTRY (48 decks)

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