W3 From atoms to molecules l Flashcards
What do double bonds represent?
The sharing of two pairs of electrons
What abbreviations can be use for ch3, ch2ch3 and ch2ch2ch3?
Me-
Et-
Pr-
What is an empirical formulae?
Lowest whole number ratio of elements forming a compound
How do you find the empirical formulae?
- Obtain mass of each element (grams). If % composition assume 100g and convert to mass
- Calculate the Number of moles: grams/molar mass
- Divide the no. of moles of each element by the one with the smallest value
- Multiply the results of step 3 by the smallest integer which will convert them all to whole numbers (not always necessary)
Organic chemistry definition
The chem of C compounds based around C-H bonds (Having at least 1 C-H bond)
What are the 6 ways to represent organic molecules? (structures)
1.Molecular
2.Functional
3. Condensed/shortened
4. Full/Displayed, Condensed, Skeletal
How do you calculate DBE (Double bond equivalent)?
- need to memorise
DBE= (2C + 2 + N - H - Hal) / 2
Define Elements:
Substances containing atoms of only one type (O2, N2 and Cl2
Define Compounds:
Atoms of two or more different elements joined together (NaCl, H2O)
Define molecule
Smallest particle in an element or compound that still possesses the characteristics of that molecule or compound.
Define Molarity
Number of moles of solute per litre of solution.
(Molarity (M) is the most widely used unit for concentration. The unit of molarity is mol/l or M.)
Define:
Atomic Number:
Mass Number:
Isotopes:
=Number of protons in the nucleus
=Number of protons + neutrons in the nucleus
=Same number of protons but different number of neutrons. Same atomic number but different mass numbers
Define Relative Mass (Atomic Mass):
How is it calculated? (calculation)
weighted average of all isotopes
* [(mass of isotope 1) x fraction of atoms of isotope1] + [(mass of isotope 2) x fraction of atoms of isotope 2] etc…
Define Molecular weight (Molecular Mass):
Units?
Mass of a molecule of a substance. The units
for molecular weight are atomic mass units (amu).
Define Molar mass:
Units?
Mass of one mole of a substance.
Molar mass is reported in grams per mole or g/mol.
