Atoms, Ions and Compounds

Question 1

State the relative masses and purposes of protons, neutron and elecrons

Answer 1

• Protons: relative mass of 1, determines the atomic number
• Neutrons: relative mass of 1, determines atomic mass + P
• Electrons: relative mass of 1/1836, determines chemical / ionic charges

Question 2

Difference between ATOM vs ION vs ISOTOPE

Answer 2

1. Atom = having no charge, with same number of protons and neutrons
2. Ion = charged particle, same proton number
3. Isotope = differing neutron number, uncharged with same proton number

Question 3

What makes “Carbon - 12” important in “Mr”

Answer 3

• This is the agreed universal standard when comparing masses, having itself 12u

u = atomic mass unit

Question 4

Define Relative Atomic Mass

Answer 4

• This is the weighted mean mass of an element relative to 1/12th of a carbon-12 atom

of an ATOM of an ELEMENT…..

Question 5

Define Relative Isotopic Mass

Answer 5

• Mass of an isotope relative to 1/12th of a carbon-12 atom

Question 6

What component of an atom determines the physical and chemical properties?

Answer 6

• Physical: Number of neutron / size of the nucleus, (such as intermolecular forces)
• Chemical: Number of electrons in outer shell / full atom

Question 7

Why does “Relative Isotopic Mass” not have any units?

Answer 7

• Due to this being a COMPARITIVE RATIO between multiple isotopes involved to calculate this

Question 8

What does Relative Atomic Mass depend on?

Answer 8

1. Percentage abundance of the Atom
2. The Relative Isotopic Mass ot Atoms

Question 9

Name some examples of Physical and Chemical Properties of Elements….

Answer 9

1. Reactivity, Ionisation Energies ect
2. Melting and Boiling points……

Question 10

What is 1/12th of a Carbon-12 atom the same as?

Answer 10

Same as 1 single atomic mass unit&raquo_space;(u)«

hence why we use it as a comparitive atom in “Mr”……..

Question 11

How is isotope abundance determined via spectroscopy?

Answer 11

• Ions of same charge = same KE
• Heavier Ions = slower (vice versa for lighter ions) due to slightly different mass numbers
• Hence m/z ratio calculated with these values

Question 12

Explain the basics behind Mass Spectroscopy….

Answer 12

1. Sample is **vapourised and ionised **to form positive ions
2. Ions will be accelerated via an opposite charge, and may be deflected via positve field
3. Ions wil reach the detector, where positive ions gain electrons

Question 13

What is a Mass Spectrometer?

Answer 13

• instruent thats measures the mass-to-charge ratio of isotopes, to find their abundances.

Time Taken = Found atomic masses
Charge Sizes = Abundance of that specific Isotope

Question 14

Why may drastic mass spectrums occur?

Answer 14

• This may be due to the re-ionisng of some ions (giving greater positive charges)

Question 15

Give the Nitrate , sulfate , carbonate ionic charges

Answer 15

1. NO3-
2. SO42-
3. CO32-

Question 16

Give the Hydrogencarbonate, hydroxide, phosphate ionic charges

Answer 16

1. HCO3-
2. OH-
3. PO43-

Question 17

Give the zinc, silver and ammonium ionic charge

Answer 17

1. Zn2+
2. Ag2+
3. NH4+

Question 18

Why can’t we add protons and neutron simply when taking relative atomic masses?

Answer 18

• Due to STRONG NUCLEAR FORCE, holding the protons and the neutron together within nucleus
• Hence, small mass decrease when atom is chemically bonded!