Atoms, ions and compounds Flashcards
Define isotope
Atoms of the same element with different numbers of neutrons and different atomic masses
Explain why the chemical reaction of isotopes of the same element are the same
- Chemical reactions involve the electrons surrounding the nucleus
- Different isotopes have the same number of electrons
- Number of neutrons has no effect on reactions of an element
What is an ion?
A positively or negatively charged atom, where the number of electrons is different from the number of protons
What is an oxidising agent?
A substance that has the ability to oxidise other substances ( accept their electrons )
What is a reducing agent?
An element or compound that loses or donates an electron to an electron recipient ( oxidising agents )
Define relative isotopic mass
The mass of an isotope relative to 1/12 of the mass of an atom of carbon-12
Define relative atomic mass (Ar)
The weighted mean mass of an atom of an element relative to 1/12 of the mass of an atom of carbon-12
What is the equation to calculate relative atomic mass?
Relative atomic mass = sum of (isotope mass x percentage abundance of isotope) / 100
How do you find the percentage abundance of an isotope?
By using a mass spectrometer
How do mass spectrometers work?
- Mass spectrometers vaporising a sample and then ionising to form positive ions
- The ions are accelerated, heavier ions move more slowly and are more difficult to detect than lighter ions so the ions of each isotope are seperated
- The ions are detected on a mass spectrum as a mass-to-charge ratio (m/z)
- Each ion reaching the detector adds to the signal, so the greater the abundance, the larger the signal
What are the units for molar masses?
gmol^-1
What is the formula of a nitrate ion?
NO3
Charge = 1-
What is the formula of a carbonate ion?
CO3
Charge = 2-
What is the formula of a sulphate ion?
SO4
Charge = 2-
What is the formula of a hydroxide ion?
OH
Charge = 1-
