foundations in chemistry Flashcards
what is relative atomic mass (Ar)?
Ar is the weighted mean mass of an atom relative to 1/12th of the mass of an atom of carbon-12
what does Ar take into account?
the percentage abundance of each isotope and the relative isotopic mass of each isotope.
what is relative isotopic mass?
relative isotopic mass is the mass of one isotope relative to 1/12th of the mass of one atom of carbon-12
how would you work out the percentage abundance of an isotope to work out relative atomic mass?
using a mass spectrometer
how much roughly is 1u (atomic mass unit)
mass of one proton
what is the relative mass of one electron
1/1836
what does the principal quantum number, n refer to?
the shell number/energy level number
what is the maximum number of electrons which can be held in shell:
1
2
3
4
n=1–>2 electrons
n=2–>8 electrons
n=3–>18 electrons
n=4–> 32 electrons
electron shells themselves are split into sub-shells. what are these labelled?
s, p, d and f
which sub shells are in each electron shell?
n=1 shell has the s sub shell
n=2 shell has the s and p sub shell
n=3 shell has the s p and d sub shell
n=4 shell has the s p d and f sub shell
what is the maximum number of electrons each sub shell can hold?
s sub shell can hold 2 electrons max.
p sub shell can hold 6 electrons max.
d. sub shell can hold 10 electrons max.
f. sub shell can hold 14 electrons max
the s, p, d, and f sub shells are themselves divided into further atomic orbitals. How many orbitals does each sub shell contain?
s sub shell- 1 s-orbital
p sub shell- 3 p-orbitals
d sub shell- 5 d-orbitals
f sub shell- 7 f-orbitals
how is the direction of the electron spin represented in an atomic orbital?
a box with arrows. the box represents the atomic orbital. arrows for the electrons. clockwise spin- upwards arrow
anticlockwise spin- downwards arrow
what is an atomic orbital?
a region of space in an atom that can hold up to 2 electrons with opposite spins
what are the 4 types of orbitals?
s, p, d and f
what is the rule for metals in term of bonding?
metals always lose electrons to form positive ions/cations
what is a polyatomic ion?
An ion that contains more than one element bonded together
list the 8 polyatomic ions we need to know and their charges
ammonium- NH4 +
Hydroxide-OH -
nitrate- NO3 -
carbonate-CO3 2-
sulfate- SO4 2-
zinc- zn 2+
silver- Ag+
phosphate- PO4 3-
what is amount of substance?
what we use to measure the number of particles
what is 1 mole?
amount of substance that contains 6.02x10^23 particles
what is relative formula mass/molar mass and its units?
sum of the atomic masses, g/mol -1
how do you work out no. of molecules?
1) work out moles of entire compound
2) multiply moles by avogadros constant
how do you work out no. of atoms of one element in a compound? (3)
1) work out moles of entire compound
2) if the required element has no little number next to it then it remains the same no. of moles/ if it has a number e.g a 3 then multiply the mol. by the number
3) multiply by Avogadro’s constant
how do you work out total no. of atoms in a compound?
1) work out total no. of moles for each individual element by working out mol of total compound then comparing it to the small number next to the element
2) add these together
3) multiply by avogadros constant