Lecture notes
KCL Biomedical Science 4BBY1020 Chem For Biosciences
- Institution
- Kings College London (KCL)
Lecture notes, a few may be missing but majority are there
[Show more]
3 reviews
By: abigailkrystle • 1 year ago
By: sugietaganaeshalingam • 2 year ago
By: Tash432 • 3 year ago
Content preview
Lecture 2Atoms, compounds and chemical bonding
Dr A. James Mason
Recall the simple model of atomic structure in terms of protons, neutrons and electrons
• Movement from one orbital to
another leads to
absorption/emission of
electromagnetic radiation
• Energy levels determine types of
bonding, determine structure and
shape
• See using light energy is emitted or
absorbed at discrete wavelengths
• Electrons at discrete positions from nucleus, different levels of
energy which separate them
Describe the shapes, arrangements and relative energies of s, p and d atomic orbitals
• Electrons are confined within specific volumes of
space called orbitals.
• Orbitals grouped into shells: s, p, d, f
• 4s orbital of lower energy level therefore fills up
before 3d orbital
,Predict the electron configuration of isolated atoms of the major elements commonly found in
biological molecules (H, C, N, O, P, S) and relate this to their valence and reactivity
• Valency - “The maximum number of univalent atoms (originally hydrogen or chlorine atoms)
that may combine with an atom of the element under consideration, or with a fragment, or
for which an atom of this element can be substituted.” – IUPAC
• Valency determined by Valence shell = the highest occupied shell
• Oxygen electron arrangement (2, 6) ; Highest occupied is shell 2 therefore it is the valence
shell
• 2 more electrons required to fill oxygen valence shell (to make 8 electrons in the shell)
• Therefore, Valency is how many electrons are required to fill valence shell
• Valency:
H=1
C=4
N=3
O=2
P=3
S=2
,Define the term “electronegativity”, describe electronegativity trends in the periodic table, and
use electronegativity values to predict whether ionic or covalent bonding will occur between two
atoms.
• Electronegativity - Ability of an atom to attract electrons towards itself
• Always something in between (indicated by red area); can have covalent bonds with partial
ionic character and covalent bonds with partial ionic character, All dependent on
electronegativity of both atoms
, Understand the nature of ionic, covalent and dative covalent bonds, and lone pairs of electrons,
and depict these using Lewis dot symbols
Outline how molecular orbitals are formed from atomic orbitals and distinguish between bonding,
anti-bonding and non-bonding orbitals
• 2 atoms come together, therefore atomic orbitals come together, form a new molecular
orbital
• Each atomic orbital takes a place in the molecular orbital. One forms a low energy bonding
orbital, the other forms a high energy bonding orbital
• Look at example on right:
• The orbital at the bottom is filled
therefore high density therefore
Anti – Bonding orbital.
• The orbital at the top is empty
therefore low density therefore Bonding orbital
• Electrons naturally occupy the bonding orbital, which is lower in energy
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller nahiyan. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £4.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
67474 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now