TBBOL- Week 1

How are elements listed?

Increasing atomic mass.

What are the three subatomic particles?

Protons, neutrons and electrons.

What is the definition of atomic number?

The number of protons in the nucleus.

What is the definition of atomic mass?

The mass of protons and neutrons in the nucleus.

Isotopes are forms of an element that have the same atomic number but a different number of?

Protons.

How many isotopes do carbon have?

15.

What are the two most stable isotopes of carbon?

Carbon-12 and Carbon-13.

How many elements do humans require?

25.

How many elements are essential for all biological systems?

11.

What are the three most common atoms in the human body?

Carbon, hydrogen and oxygen.

What do all stars produce when they burn hydrogen?

Helium.

What is the name of the process which stars use to produce helium?

Nuclear fusion.

What stars run out of hydrogen, they fuse with helium to accumulate what elements?

Lithium, beryllium, boron and carbon.

The rest of the natural occuring elements are results of what?

Supernovas.

What must elements be in order to be used by our biological systems?

They must be abundant in the environment and in an easily extractable form.

What type of elements are the most abundant?

Lighter elements.

When elements show similar properties, how is it determined which one is selected?

The one that is most abundant in the crust, oceans or atmosphere.

What does carbon form when it binds to other elements?

Stable and complex molecules.

What is an element defined as?

A single, simple substance that cannot be split into more separate substances by chemical means.

What is an atom defined as?

The smallest particle into which an element can be divided, while retaining the properties of the element.

What do electrons occupy that is larger than the nucleus?

An extranuclear space.

According to quantum numbers, what is quantised?

The energy of electrons.

What is the name of the shell holding the electrons furthest from the nucleus?

The valence shell.

What is the name of electrons located in the shell furthest from the nucleus?

Valence electrons.

What do valence electrons determine?

The reactivity of the atom.

What is the difference between atomic and external configuration?

Atomic configuration takes into account all the electrons an atom possesses. External only considers valence electrons.

What is the name of the volumes of space electrons are confined to move within?

Orbitals.

What are the four orbitals?

S, P, D and F.

What are the four shapes of orbitals respectively?

Spherical, dumb bell, four-leaved clover and raspberry.

What is the name of a group of equivalent orbitals?

A subshell.

What is the Aufbau principle?

Filling orbitals based on progressively higher energy.

What is the Pauli exclusion principle?

An orbital contains no more than two electrons.

What is Hund’s rule?

Degenerate orbitals are partially filled before any orbital is completely filled.

What is the definition of electron excitation?

When an electron is provided with the right amount of energy, it can jump from a low energy level to a higher energy level.

What is the definition of electron relaxation?

When an excited electron returns to its ground state, it emits energy in the form of electromagnetic wavelength.

Electromagnetic radiation are characterised by their wavelength which is inversely proportional to their what?

Frequency.

What is the frequency of a photon absorbed or emitted directly proportional to?

The energy difference between the excited and ground state.

What is ionisation energy?

The amount of energy required to ionise a mole of a given element.

Elements with low ionisation energies are good what?

Reducing agents.

What is the trend with ionisation energy?

Decreases from top to bottom in groups and increases left to right in periods.

Are cations positively or negatively charged?

Positively.

Are anions positively or negatively charged?

Negatively.

Why do electron pairs repel each other?

To maximise separation.

Do non-bonding pairs repel valence electrons more or less than bonding pairs?

More.

What is steric number?

The number of atoms bonded to a central atom and the number of lone pairs.

What is hybridisation?

The process through which atomic orbitals combine to generate new hybrid orbitals.

How many 2s electrons are promoted in the first instance?

One.

What are the three scenarios of atomic orbitals that can be formed?

Sp3, sp2 and sp.

What does an unhybridised electron result in?

A double bond.

What does two unhybridised electrons result in?

A triple bond.

What is the orientation of the four sp3 orbitals?

Tetrahedral.

What is the orientation of the three sp2 orbitals?

Trigonal planar.

What is the orientation of the two sp orbitals?

Linear.

What are pairs of electrons occupying the same orbital called?

Lone pairs.

What is the Octec rule?

To reach maximum stability,, main group elements seek to gain 8 electrons in their valence shell.

What is hypervalency?

A phenomenon where main group elements found in the s and p block of the periodic table are found to accommodate more than 8 electrons in their external shell.

What can be the maximum amount of valence electrons in hypervalent compounds?

16.

How is sulfur able to make 6 bonds?

It gives away two of its electrons.

How is a covalent bond formed?

When two atoms share a pair of electrons.

What is the valence bond theory?

Electrons involved in a chemical bond are localised between two atoms and bonds are formed when valence orbitals overlap.

What is the advantage of the valence bond theory?

It allows us to readily understand the shape and reactivity of biological molecules.

What is the disadvantage of the valence bond theory?

It cannot explain photochemical reactions.

What is the molecular orbital theory?

Atomic orbitals combine to form molecular orbitals and atomic orbitals interact with each other like waves- they can either be constructive or destructive.

What do constructive interferences lead to?

Bonding MOs.

What do destructive interferences lead to?

Antibonding MOs.

What is the advantage of the MO theory?

It allows us to rationalise curly arrow mechanisms.

What is the disadvantage of the MO theory?

It can be conceptually challenging.

What does the combination of n atomic orbitals generate?

N molecular orbitals.Wh

What are the two types of bonding molecular orbitals?

Sigma and pi.

How are sigma orbitals originated?

The head-on overlap of atomic orbitals.

How are pi orbitals originated?

The side-on overlap of atomic orbitals.

What does electronegativity influence?

The energy of valence electrons.

What can covalent bonds be classified as depending on the energy difference between the interacting valence electrons?

Polar or non-polar.

What can the separation of charges observed in polar bonds result in?

The formation of permanent dipoles.

What happens when a metal donates electrons to a non-metal?

It generates a cation.

What happens when a metal accepts an electron from a metal?

It generates an anion.

How is a dative covalent bond formed?

When the pair of electrons shared to form a covalent bond comes from a single atom.

What are dative bonds common to?

The bonding of metal ion to organic ligands.

What are coordination complexes?

Compounds consisting of a coordination centre surrounded by molecules capable of coordinating with the central atom through dative bonds.

What is coordination number?

The number of ligands attached to the central metal.

What does the Kepert model ignore?

Non-bonding electrons.

What is the name of the complex when a metal that forms a complex with a ligand capable of forming more than one coordinate bond?

The chelate.

What is conjugation?

The ability of electrons in a system of double bonds to spread over the whole p system, rather than staying localised on a specific double bond.

What are conjugated double bonds separated by?

A single bond.

What is resonance?

A method of describing delocalisation of electrons in molecules where bonding cannot be rationalised using Lewis structures.

What is homolytic fission?

The process through which a bond is broken, and each fragment retains one of the originally bonded electrons.

What does homolytic fission form?

Radicals.

What is used to measure the strength of a bond?

Bond dissociation energy.

What is heterolytic fission?

The process through which a bond is broken and both the originally bonded electrons end up on one of the fragments.

What does heterolytic fission generate?

Ions.

What does a closed pi system give way to?

Aromatisation.