Elements of life Flashcards
What is the mass number?
The number of protons plus the number of neutrons
What is an isotope?
Atoms of the same element but with a different mass number because of having a different number of neutrons
What is Mass spectrometry?
The measure of the atomic mass of particles (atoms or molecules)
How does Mass spectrometry work?
Atoms or molecules are ionized and form cationos and are then separated based off mass and charge.
What is nuclear Fusion? and what must happen for it to occur?
When two lighter nuclei are combined to make a havier nucleus of a new element.
The nuclei must come very close to each other.
12-6-C. What do the two numbers represent?
The 12 is the mass.
6 is the number of protons (atomic mass)
What happens when electrons around an atom absorb light?
The electrons are raised from their ground state into an excited state.
What does the absorption spectrum look light and what does it signify?
It is a colored spectrum with black lines that signify what wavelengths of light have been absorbed by an atoms electrons.
What happens after and electron moves to its excited state?
It will fall back to its ground state which causes a photon to be released.
What does an emission spectrum look like? and what does it signify?
Black spectrum with colored lines that signify what frequency of light has been released.
What is Bohrs theory?
The theory of absorption and emission spectrum. It was the first indication of electrons. It also said that energy is quantised. Also linked the behavior of light as a particle and a wave
2 equations related to Bohrs theory:
Speed of light = Frequency x Wavelength
Energy of a photon = Plancks Constant x Frequency
What is the order of subshells? and how many electrons in each?
S (2 electrons), P (6 electrons), D (10 electrons) , F (14 electrons)
How do electron pairs orbit?
Opposite Directions
What is the shape of the S Subshell?
Spherical
What is the shape of the P Subshell?
Figure of 8
Describe how electrons fill sub shells:
They fill from the inside out and fill each pair of electrons evenly
Why do electron sub shells fill the way they do?
Because they fill up with the lowest energy configuration possible. Efficiency
Which part of the periodic table corresponds to S, P, D?
S: Group 1 and 2
P: Group 3 to 8
D: Transition Metals
How did Mendeleev arrange the periodic table? How is it arranged now?
Mendeleev: In order of relative atomic mass
Now: In order of number of protons
Describe covalent bonding?
- Between two no-metalic atoms
- They share electrons
Describe a dative covalent bond?
A covalent bond but one electron donates more electrons than the other.
Describe the properties of a covalent bond.
- Very strong bond so breaking it is very hard (requires more energy)
- Electrostatic attraction between molecules is low so separating them is easily done (requires little energy)
How are molecular shapes formed?
Because regions of electron density are negatively charged and so repel each other. They move as far away as possible.
Bond angle: Linear
180*
Bond angle: Trigonal planar
120*
Bond angle: Tetrahedral
109.5*
Bond angle: Triganal bi pyramidal
120* and 90*
Bond angle: Octahedral
90*
What is a mole? and what is its value?
A quantity of something
6.02x10^23
Equation for calculating the number of moles
Mass / Molar mass
What is the empiracle formula?
The simplest molecular formula
What is a molecular formula?
Condensed formula (atoms grouped together)
Why might a yield be less than expected?
- Loss of reactants
- Side reactions
- Impurities
- Temperature or pressure change
- Reaction not gone to completion
How do you calculate your yield?
( Experimental yield / theoretical yield ) x 100
What is water crystallization?
Water molecules are trapped in the molecule of crystal. This is a hydrated crystal
How can water composition of a hydrated crystal be calculated?
Heating and evaporating the water and measuring the mass change.
What does the equation for a hydrated crystal look like?
CuSO4 * 5H20
What are the properties of S block elements?
- Elements become more metallic as you go down the group
- S block metals are weaker than other metals
- They are all very reactive and so cannot be found pure
What is first ionization enthalpy?
The energy required to remove and electron from the outer shell of an atom when it is in a gas state.
What ion is formed when a gas is ionized during first ionization enthalpy?
Positive ion (cation)
What is a Cation?
A positive ion
What is an anion?
Negative ion
What are the first ionization enthalpy trends?
- The energy required increase as you move across the period because there are more protons holding the electrons in place
- As you move down a group the energy required gets smaller because there are more shells and more electron shielding
What is the equation for the first and second ionization reaction with calcium?
Ca ==> Ca+ + e-
Ca+ ==> Ca2+ + e-
How do group 2 atoms react with oxygen?
They bond to make an oxide:
2M + O2 ==> 2MO
How do group 2 atoms react with water? and what is produced?
They make hydrogen
M + 2H2O ==> M(OH)2 + H2
What happens when you heat carbonates?
They form an oxide and Carbon dioxide
MCO3 ==> MO + CO2
What are the properties of thermally decomposing group 2 carbonates? and why?
- Harder to decompose down the group because the lower groups have a lower charge density and so form a more stable carbonate.
- MgCO3 is less stable than CaCO3 so MgCO3 more readily breaks down
How do group 2 oxides and hydroxides react with acids?
They form salts. e.g.
MO + HCl ==> MCl2 + H2O
M(OH)2 + H2SO4 ==> MSO4 + 2H2O
Why are acids acidic?
Because they contain a H+ ion that dissociates in water
Why are alkalis alkali?
Because they contain a OH- ion that dissociates in water.
What happens when you combine a Acid and alkali? What is formed and how do they neutralise?
Acid + Alkali ==> Salt + Water
H+ + OH- ==> H20
What is a base?
Any substance that accepts a H+ ion
What happens when an acid and water combine? and what is formed?
The water accepts the H+ ion and forms an oxonium ion.
e.g.
HCl + H2O ==> H3O+ + Cl-
What is the order for sub shells?
1s2 2S2 2P6 3S2 3P6 4S2 3D10 4P6 4D10 4F14
What is the relative formula mass?
The sum of the Relative atomic masses of atoms in a molecule
4 equations to make ionic salts?
Acid + Alkali ==> Salt + Water
Acid + Base ==> Salt + water
Acid + carbonate == > Salt + Water + Carbon dioxide
Acid + Metla ==> Salt + Hydrogen
Describe metallic bonding?
Positive ions surrounded by a sea of delocalised electrons
