C2 - Atoms, ions and compounds Flashcards
What is the structure of an atom?
-Central nucleus consisting of protons and neutrons
-Electrons orbiting nucleus in shells
What is the charge of a proton?
+1
What is the charge of a electron?
-1
What is the charge of a neutron?
Neutral
What is the relative mass of a proton?
1
What is the relative mass of a electron
1/2000
1/1836
What is the relative mass of a neutron?
1
Where is the majority of an atom’s mass?
Nucleus
What is the overall charge of an atom?
0
What is the role of neutrons in an atom?
“provide glue that holds nucleus together despite electrostatic repulsion between oppositely charged protons and electrons”
What is the atomic number
Number of protons in the nucleus of an atom
Z
What’s an isotope
Atoms of the same element with different numbers of neutrons and different atomic masses
What is mass number?
Sum of protons and neutrons in the nucleus
A
How is an isotope represented
With its mass number
How does the reactivity of isotopes differ?
Same number of electrons
So same chemical reactions
What is an ion?
Positively or negatively charged atoms or group of atoms where the number of electrons is different from the number of protons
What are cation?
Positively charged ions
What are anions?
Negatively charged ions
What is mass defect
Small amount of mass lost due to the strong nuclear force holding together protons and neutrons
Why is mass unit, u, used?
Working in kg would be awkward
What is mass of carbon-12
12 atomic mass units (u)
What is relative isotopic mass?
Mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12
What is relative atomic mass?
Ar
Weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12
What is relative formula mass?
Weighted means mass of the formula unit of a compound compared with 1/12th of the mass of an atom of carbon-12
What is relative molecular mass
Mr
Weight mean mass of a molecule of a compound compared with 1/12th of the mass of an atom of carbon-12
What does the weighted mean mass take into account
Percentage abundance of each isotope
Relative isotopic mass of each isotope
How is the percentage abundance of isotopes in a sample of an element found experimentally
Using a mass spectrometer
How does a mass spectrometer work?
1) Sample place in the mass spectrometer
2) Sample vaporised and ionised to form positive ions
3) Ions accelerated
4) Heavier ions move slower and are more difficult to deflect so ions of isotope are separated
5) Ions are detected on a mass spectrum as a mass to charge ratio m/z
6) Greater abundance, larger signal
M/z ratio formula
Relative mass of ion/ relative charge of ion
How do you calculate relative atomic mass from abundance of isotopes
( Percentage adundance x atomic mass ) / 100
What is a binary compound
A compound containing two elements onky
What is a polyatomic ion
Ion containing more than one atom
Ammonium ion formula
NH4+
Hydroxide ion formula
OH-
Nitrate ion formula
NO3-
Nitrite ion formula
NO2-
Hydrogen carbonate ion formula
HCO3 -
Manganate (VII) ion formula
Permanganate ion
MnO4 -
Carbonate ion formula
CO3 2-
Sulfate ion formula
SO4 2-
Sulfite ion formula
SO3 2-
Dichromate (VI) ions formul
Cr2O7 2-
Phosphate ion formula
PO4 3-
Zinc ion formula
Zn 2+
Silver ion formula
Ag +
What is a formula unit?
Compound worked out from ionic charge ?
States in equations
(g) gas
(l) liquid
(s) solid
(aq) aqueous
