Unit 1- Inorganic chemistry Flashcards
A photon carries energy proportional to what?
The frequency of radiation
The photons in which frequency of radiation can transfer greater amounts of energy?
Those in high frequency radiation transfer greater amounts of energy
What can happen to the electrons within atoms when energy is transferred to these atoms?
The electrons can be promoted to higher energy levels
When does an atom emit a photon of light energy?
When an excited electron moves from a higher energy level to a lower energy level
What happens in absorption spectroscopy?
Electromagnetic radiation is directed at an atomised sample, the radiation is then absorbed as electrons are promoted to higher energy levels
What happens in emission spectroscopy?
High temperatures are used to excite the electrons within atoms, as the electrons drop to lower energy levels, photons are emitted
In atomic spectroscopy, what is the concentration of the element within a sample related to?
The intensity of light emitted or absorbed
What are the 4 different shapes of orbitals?
s, p, d and f
How do electrons behave in an atom?
As standing waves. These are waves that vibrate in time but do not move in space. There are different sizes and shapes of standing wave possible around the nucleus, known as orbitals
How many electrons can an orbital hold?
A maximum of 2
How many electrons can an orbital hold?
A maximum of 2
What is the order of the electromagnetic spectrum from highest to lowest energy?
Gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves and radio waves
Electrons within atoms have fixed amounts of energy called…?
Quanta
It is possible to describe any electron within an atom using four quantum numbers, what are these and what do they tell us about the electron?
- principal quantum number (n)- indicates the main energy level for an electron and is related to the size of the orbital
- angular momentum number (l)- determines the shape of the subshell and can have values from zero to n-1
- magnetic quantum number (m)- determines the orientation of the orbital and can have values between -l and +l
- spin magnetic quantum number (s)- determines the spin and can have values of +1/2 or -1/2
What are the 3 rules that determine how electrons within atoms are arranged?
- the aufbau principle
- Hund’s rule
- the Pauli exclusion principle
What is the aufbau principle?
Electrons fill orbitals in order of increasing energy
What is Hund’s rule?
When degenerate orbitals are available, electrons fill each singly, keeping their spins parallel before spin pairing starts
What is the Pauli exclusion principle?
No two electrons in one atom can have the same set of 4 quantum numbers, therefore, no orbital can hold more than two electrons and these two electrons must have opposite spins
In an isolated atom, what can be said about the orbitals within each subset?
They are degenerate (have the same energy)
The periodic table can be split into 4 blocks (s, p, d and f), which correspond to what?
The outer electronic configuration of the elements within these blocks
How are electron pairs arranged?
To minimise repulsion and maximise separation
What are the names for the arrangement of electron pairs around a central atom for two through to six electron pairs?
two electron pairs= linear three electron pairs= trigonal planar four electron pairs= tetrahedral five electron pairs= trigonal bipyramidal six electron pairs= octahedral
What is the order of electron pair repulsions in order from most repulsion to least repulsion?
- bonded pair/bonded pair (most repulsion)
- non-bonded pair/bonded pair
- non-bonded pair/non-bonded pair (least repulsion)
What are the d-block transition metals?
Metals with an incomplete d subshell in at least one of their ions
The filling of d orbitals follows the aufbau principle, with the exception of which two elements and why is this?
Chromium and copper, these exceptions are due to the special stability associated with the d subshell being half filled or completely filled
When atoms from the first row of the transition elements form ions, what electrons do they lose first?
The 4s electrons are lost first rather than the 3d electrons
What oxidation number do uncombined elements have?
zero
What is the oxidation number of ions containing single atoms?
The oxidation number is the same as the charge on the ion
In most of its compounds, what is oxygen’s oxidation number?
-2
In most of its compounds, what is hydrogen’s oxidation number?
+1
What must the sum of all the oxidation numbers in a neutral compound add up to?
zero
What must the sum of all the oxidation numbers in a polyatomic ion add be equal to?
The charge on the ion
What can oxidation be defined as?
An increase in the oxidation number
What can reduction be defined as?
A decrease in the oxidation number
What are oxidising agents often?
Compounds containing metals in high oxidation states
What are reducing agents often?
Compounds containing metals in low oxidation states
What are ligands?
Negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds
What is a dative covalent bond?
a covalent bond (a shared pair of electrons) in which both electrons come from the same atom
What are the classifications of ligands and give examples of each?
- monodentate (NH3, Cl-)
- bidenatate (oxalate ion)
- hexadentate (EDTA)
What is the coordination number of a ligand?
The total number of bonds from the ligands to the central transition metal
What can be said about the d orbitals in a complex of a transition metal?
They are no longer degenerate
When does the splitting of d orbitals to higher and lower energies occur?
When the electrons present in approaching ligands cause the electrons in the orbitals lying along the axes to be repelled
What is the difference between strong and weak field ligands?
Strong field ligands cause a large difference in energy between subsets of d orbitals, weak field ligands cause a small energy difference
What are heterogeneous catalysts?
Catalysts which are in a different state to the reactants
What are homogeneous catalysts?
Catalysts which are in the same state as the reactants
Why is electromagnetic radiation said to have a dual nature?
Because it can be described as both a wave and a particle
What are photons?
When electromagnetic radiation is absorbed or emitted by matter it behaves like a stream of particles. These particles are known as photons
What can be used to identify an element?
It’s characteristic emission and absorption spectra
How can the discrete lines observed in atomic spectra be explained?
If electrons, like photons also display the properties of both particles and waves
What shape are S orbitals?
Spherical
What 2 elements are not transition metals when they would be expected to be and why?
Zinc and scandium, they are not transition metals as they do no form a stable lot
What can be said about compounds of the same transition metal in different oxidation states?
They may have different colours
What is a transition metal complex?
A compound made of a transition metal ion covalently bonded to ligands
What is the spectrochemical series?
The order that ligands can be placed in based on their ability to split d orbitals
What are the 3 main indicators of a transition metal?
- Can produce ions with different valencies
- Make coloured compounds
- Have catalytic uses
