Module 2: Chapter 2 - Atoms, Ions, and Compounds Flashcards
What is the relative charge of a proton?
+1
What is the relative charge of an electron?
-1
What is the relative charge of a neutron?
0
What is the relative mass of a proton?
1
What is the relative mass of an electron?
1/1836
What is the relative mass of a neutron?
1
What is the atomic number?
The number of protons in the nucleus of an atom
What is the mass number?
The sum of the protons and the neutrons in the nucleus of an atom
Why is an atom neutral?
Because the number of protons is equal to the number of electrons
What are isotopes?
Isotopes are atoms of the same element and therefore contain the same number of protons but contain a different number of neutrons and therefore have different mass numbers
What are ions?
Charged particles formed when atoms gain or lose electrons to gain stability
What is relative isotopic mass?
The mass of an atom compared (relative) with 1/12th the mass of carbon-12
What is relative atomic mass, Ar?
The weighted mean average mass of an atom of an element compared with 1/12th the mass of an atom of carbon-12
What is a mass spectrometer?
An analytical piece of equipment used to find relative abundances of isotopes in a sample of an element
Explain how mass spectroscopy works
The sample enters the spectrometer and is vaporised. An electron beam is fired at the sample to knock out an electron from each atom, ionising the sample to form 1+ positive ions. The ions are accelerated by an electric field towards a negatively charged plate. The ions are allowed to drift through the flight tube through a magnetic field which separates the isotopes according to mass (lighter ions are accelerated and deflected the most). They are detected when the ions arrive at the detector. This feeds a signal into a computer which produces a graph of the relative abundance of ions against the mass to charge ratio
What is the graph produced by a mass spectrometer called?
Mass spectrum/spectra
Describe a mass spectrum
It has relative abundance % on the y axis and the mass to charge ratio on the x axis
35 = ³⁵Cl⁺
37 = ³⁷Cl⁺
70 = (³⁵Cl-³⁵Cl)⁺
72 = (³⁵Cl-³⁷Cl)⁺
74 = (³⁷Cl-³⁷Cl)⁺
What is the international standard for the measurement of relative mass?
1/12th the mass of an atom of carbon-12
What is the unit of atomic mass?
Unified atomic mass unit, amu
What is the role of neutrons?
Neutrons help to keep a nucleus stable by moderating the repulsive forces between the protons in the nucleus
What is the symbol for mass number?
A
What is the symbol for atomic number?
Z
What is the mass of carbon-12?
12 amu
What ion will have the shortest time of flight and reach the detector first is mass specroscopy?
The ion with least mass as it is the lightest and will therefore travel the fastest through the flight tube
For an ion with a 1+ charge, what is the m/z (mass-to-charge) ratio equivalent to?
The relative isotopic mass of the ion
How do metals form ions?
Lose electrons to form cations (positive ions)
how do non-metals form ions?
Gain electrons to form anions (negative ions)
What charge ions do transition metals form?
Transition metals can form several ions with different charges
What is a binary compound?
A compound which contains 2 elements only
How do you name a binary compound?
Use the name of the first element but change the ending of the second element’s name to -ide (i.e sodium oxide)
What comes first when naming an ionic compound?
A metal is always named before the non-metal
What is the formula of a zinc ion?
Zn²⁺
What is the formula of a silver ion?
Ag⁺
What is a polyatomic ion?
An ion which contains atoms of more than 1 element bonded together
What is the molecular formula of an ammonium ion?
NH₄⁺
What is the molecular formula of a hydroxide ion?
OH⁻
What is the molecular formula of a nitrate ion?
NO₃⁻
What is the molecular formula of a nitrite ion?
NO₂⁻
What is the molecular formula of a hydrogencarbonate ion?
HCO₃⁻
What is the molecular formula of a manganate(VII) (Permanganate) ion?
MnO₄⁻
What is the molecular formula of a carbonate ion?
CO₃²⁻
What is the molecular formula of a sulfate ion?
SO₄²⁻
What is the molecular formula of a sulfite ion?
SO₃²⁻
What is the molecular formula of a dichromate(VI) ion?
Cr₂O₇²⁻
What is the molecular formula of a phosphate ion?
PO₄³⁻
What is the rule for writing formula from ions?
The overall charge is 0, therefore the sum of the positive charges = sum of the negative charges
How do you show in a formula if there is more than 1 of a specific ion?
A subscript after the ion indicates the number of a specific ion, and brackets are used around a polyatomic ion if there is more than 1
What are diatomic molecules?
Molecules containing only 2 atoms
What are the 7 diatomic elements?
- Hydrogen
- Nitrogen
- Oxygen
- Fluorine
- Chlorine
- Bromine
- Iodine
What is the formula of phosphorus?
P₄
What is the formula of sulfur?
S₈ (but it is normal practise to write it as S in equations otherwise everything else must be multiplied by 8)
What is the formula unit?
The empirical formula of any ionic or giant covalent compound (it is used in equations)
What are state symbols?
Small symbols used to indicate a physical state
What are the 4 state symbols?
(s) - solid
(l) - liquid
(g) - gas
(aq) - aqueous solution