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A-LEVEL CHEMISTRY 𓃘 > CHAPTER 2: ATOMS, IONS AND COMPOUNDS > Flashcards

CHAPTER 2: ATOMS, IONS AND COMPOUNDS Flashcards

1
Q

What is the mass of a proton, neutron and electron?

A 
Proton = 1
Neutron = 1
Electron = 1/1836
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2
Q

What is the definition of an isotope?

A

Atoms of the same element with different numbers of neutrons, and different masses

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3
Q

Why do isotopes have no effect on chemical reactions?

A

Because neutrons do not have an effect on chemical reactions, the transfer and sharing of electrons does. However, higher-mass isotopes will have a higher boiling and melting point, and density.

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4
Q

What is an ion?

A

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

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5
Q

What is a cation?

A

A positive ion, an atom with fewer electrons than protons.

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6
Q

What is an anion?

A

A negative ion, an atom with more electrons than protons.

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7
Q

What is the definition of relative isotopic mass?

A

Relative isotopic mass is the mass of an isotope relative to 1/12th of the mass of an atom of carbon-12.

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8
Q

How do you find relative isotopic mass?

A

Typically, you assume that it is the same as the mass number (protons + neutrons) of the isotope.

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9
Q

What is relative atomic mass?

A

Relative atomic mass is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.

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10
Q

How do you find relative atomic mass?

A

Multiply each isotopic mass by its percentage abundance and divide by 100

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11
Q

How is the percentage abundance of an isotope found?

A

A mass spectrometer.

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12
Q

What is the basic principle of a mass spectrometer?

A

1- A sample is placed in the mass spectrometer.

2- The sample is vaporised and then ionised to form positive ions.

3- The ions are accelerated. Heavier ions move slowly and are more difficult to deflect than lighter ions, so the ions of each isotope separate.

4- The ions are detected on a mass spectrum as a mass-to-charge ratio. Each ion reaching the detector adds to the signal. So, the greater the abundance, the larger the signal.

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13
Q

What is the mass-to-charge ratio?

A

Relative mass of ion / relative charge on ion

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14
Q

What is the formula for ammonium?

A

NH4 +

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15
Q

What is the formula for hydroxide?

A

OH -

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16
Q

What is the formula for nitrate?

A

NO3 -

17
Q

What is the formula for nitrite?

A

NO2 -

18
Q

What is the formula for hydrogencarbonate?

A

HCO3 -

19
Q

What is the formula for mangenate?

A

MnO4 -

20
Q

What is the formula for carbonate?

A

CO3 2-

21
Q

What is the formula for sulfate?

A

SO4 2-

22
Q

What is the formula for sulfite?

A

SO3 2-

23
Q

What is the formula for dichromate?

A

Cr2O7 2-

24
Q

What is the formula for phosphate?

A

PO4 3-

25
Q

What are the diatomic molecules?

A

H2, N2, O2, F2, Cl2, Br2, I2

26
Q

What was stated in Dalton’s atomic theory?

A

● Atoms are tiny particles made of elements

● Atoms cannot be divided

● All the atoms in a element are the same

● Atoms of one element are different to those of other elements

27
Q

What did Thompson discover about electrons?

A

● They have a negative charge

● They can be deflected by magnet and electric field

● They have very small mass

28
Q

Explain the plum pudding model

A

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

29
Q

What were Rutherford’s proposal after the gold leaf experiment?

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

30
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

● Most of atom’s mass is in the nucleus

● Most of the atom is empty space between the nucleus and the electrons

31
Q

What two assumptions are made when calculating mass number?

A

Contribution of the electron is neglected

Mass of both proton and neutron is taken as 1.0 u

32
Q

What are the uses of mass spectrometry?

A

● Identify unknown compounds

● Find relative abundance of each isotope of an element

● Determine structural information

33
Q

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

A

The elements are beryllium, boron, carbon and silicon as they require a lot of energy to transfer outer shell electrons

34
Q

What is an empirical formula?

A

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

35
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

A-LEVEL CHEMISTRY 𓃘 (16 decks)

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