Please enable JavaScript.
Coggle requires JavaScript to display documents.
Basic concepts, Lecture 1 basic concepts, Atoms, Avogadro's number…
Basic concepts
-
-
-
many biological processes would be to slow to sustain life, biological catalysts are required.
based on the chemical structure of molecules, we can determine what's there.
elements are substances that cannot be split into anything simpler, can be any state.
Compounds consist of two or more elements combined in a fixed ratio. physically and chemically different to the parent elements
Mixtures consist of two or more elements or compounds that are physically mixed, any quantity/ ratio can be used, components can be separated by a physical process.
Lecture 1 basic concepts
-
-
An element’s atomic mass is the mass of a single atom of a single, specific isotope
A proton carries a single positive charge, and electron carries a single negative charge, a neutron carries no
charge
The atomic number is equal to both the number of proton and the number of electrons in a neutral atom
-
Mole: If a dozen is 12 bananas, a mole is 6.022137x1023 bananas
A mole of any substance has a mass in grams equal to the atomic or formula mass of that substance, for
example, the mass of NaCl is 58.44, therefore its molar mass is 58.44g mol-1
-
-
Concentration is expressed as the number of moles of substance in one litre of solution = Molarity (units
mol/L or mol/dm)
-
-
-
-
When we dilute a solution, the number of moles of solute remains unchanged, but the concentration will decrease
You can use the following equation for dilution calculations: C1 x V1 = C2 x V2, where C1 is the starting
concentration, V1 is the initial volume, C2 is the final concentration and V2 is the final volume
Atoms
Atoms are electrically neutral, the nucleus consists of +ve protons and neutrons, giving the nucleus a +ve charge
Electrons surround the nucleus in designated orbitals, they have a -ve charge, they occupy a large volume but have little mass.
-
-
A= Atomic number., the number of protons ( and hence also the number of electrons) therefore the number of neutrons is mass - atomic number.
isotopes of the same element has different numbers of neutrons, unstable isotopes can give rise to radioactivity.
Carbon 14 can decay into nitrogen by a neutron breaking down to proton and an electron- known as beta decay.
In atoms electrons are found it orbitals, each orbital contains are maximum of 2 electrons
Electrons possess different spin- if a pair of electrons are in the same orbital, they must have opposing spins.
Orbitals are arranged in energy levels (shells)- larger numbers indicate that the orbital is further away from the nucleus.
each element has a characteristic relative atomic mass (RAM) dependent on the number of protons = average number of neutrons, the atomic mass of carbon is 12.011amu.
-
Molecules
-
2 = diatomic molecule (O2, N2) 3= triatomic molecules (O3 ozone, H20, CO2) More complex = NH3 (ammonia)