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Formal Assessment Task Notification Year 11 Chemistry Major Types of Chemical Structures

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Formal Assessment Task Notification Year 11 Chemistry

Major Types of Chemical Structures.

-Ionic Networks

Ionic networks are oppositely charged ions that are held together by electrostatic force this is called an ionic chemical bond, this bond allows one of the atoms outermost electrons to be permanently transferred to the other atom creating an ionic network.

I have put together an example of an ionic network to better understand the chemical bond taking place.

I have chosen to use the ionic compound Sodium Fluoride, NaF.

Atomic Structure:

When metals and non-metals react together they from an ionic compound, this is where the metal gives away electrons to the non-metal, such in this case the Fluoride gains an electron from the Sodium.

When the Sodium reacts with the Fluoride gas we get “Sodium Fluoride” a white solid.

Sodium Fluoride is soluble in waterit is used for toothpaste, mouthwash, and in in the fluoridation of drinking water and rat poison.

Na F

Ionic BondWe take it that when the ionic bond takes place the outer most electron of the Sodium atom will transfer to the Fluoride.. The network created by these atoms is referred to as an ionic lattice structure, the positive charges and negative charges create a pattern giving it this description:

Data

Qualitative Quantitative

Sodium (Na) The sodium atom will give

an electron to the fluoride

atom this ionic bond is what

connects these atoms to

create an ionic compound

through its lattice structure.

Sodium has 11 electron but

after transferring an electron

to the fluoride it has a total

of 10 electrons.

Fluoride (F) The fluoride atom gains an

electron from the sodium and

the ionic network is then

created through its

intermolecular forces of ionic

bonding.

Fluoride has 8 electrons

alone but when it gains an

electron form the sodium

atom its total number of

atoms is 9.

Sodium Fluoride, NaF

Lattice structure.

Sodium Fluoride in toothpaste.

Sodium Fluoride in mouthwash.Reference –

Art of Smart, Prelim Chemistry, https://artofsmart.com.au/hsctogether/different-chemicalstructures-of-atoms-and-elements//

Ionic Networks, Gordan Watson, 6/3/2017, https://www.youtube.com/watch?v=eIHfVS8Az0Q

Finding The Ionic Charges of Elements, 2013 Wayne Breslyn,

https://terpconnect.umd.edu/~wbreslyn/chemistry/naming/findingioniccharge.html

-Covalent Networks

A covalent network is a network that is held together by covalent bonds where atoms share

electrons, this creates strong covalent bonds and weak intermolecular forces, covalent bonds are

really strong and the lattice structure is so tightly packed this is what makes the covalent solid hard.

I have given an example of a covalent network to help understand the bond taking place visually by

a dot and cross diagram.

I have chosen to use the covalent compound Methane, CH4.

Methane is carbon covalently bonded to four hydrogens through a covalent network.

Electrons in the space between the nuclei is what we call bonding electrons, the bonding electrons

are what keeps lattice structures so strong, we observe this in the dot diagram where hydrogen

H

H H

C H

Dot and cross diagram:shares and electron with carbon, and carbon shares an electron with the hydrogen atoms the x mark

is the hydrogen electron shared and the yellow dot is the electron of the carbon being shared.

The Sabatier reaction is how methane is produced from a reaction of hydrogen with carbon dioxide

at high temperatures (around 300–400 °C). In nature methane is produced from landfills, sewers,

and even deep in the ocean, because of the water temperatures rising allowing the clathrates that

keep the methane trapped to break and set free the methane that then forms boulgers in the ocean

ground which in turn lets out bubbles of methane into the atmosphere.

Methane is a very effective greenhouse gas and is a huge part of climate change it is harmful to the

environment because it traps heat in the atmosphere.

Methane is primarily used to make light, heat and fuel, it is a flammable, colorless, oderless gas, it

is a small covalently bonded molecule, the atoms within it share electrons because they have half

full valence shells of electrons (they are non-metals).

Methane burns with a blue flame color, at a temperature around 1,960°C (blue flame has complete

combustion which means the flammability of methane is very extreme).

Data

Qualitative Quantitative

Carbon (C) The carbon atom is sharing 4

of the yellow dot electrons

with the hydrogen atoms.

Carbon has 6 electrons and

shares 4 of them while also

getting 4 from the hydrogen

atoms that are sharing.

Hydrogen (H) The 4 hydrogen atoms each

share an x marked electron

with the carbon atom.

Hydrogen has 1 electron, the

4 hydrogens each share an

electron with carbon as

carbon shares its 4 as well.

Reference –

Britannicca, Methane, Definition, Properties, https://www.britannica.com/science/methane

Doctor Scott, Ionic vs Covalent, https://learnwithdrscott.com/ionic-vs-covalent/

When methane is burnt in the air it presents a blue flame with its extreme heat.

The lattice structure of this covalent bonding is strong

and detailed:-Covalent Molecular

Covalent molecules are compounds that are held together by strong covalent bonds, formed from

two non-metals, they are arranged in a lattice structure and have strong intramolecular forces that

act as insulators so they can not conduct electricity, and weak intermolecular forces giving them low

melting points.

Covalent molecules can be formed into polymers both commercially and biologically.

Covalent molecules can be stringed together to make a chain, the example of such I have used is

ethylene.

I have created a Lewis structure example of the ethylene, C2H4 compound to properly understand

what is going on and visually take in the information presented.

Ethylene is composed of 2 carbon and 4 hydrogen, they are connected by covalent bonds, when it is

formed into a polymer it becomes a chain which is layered creating a lattice structure.

Each line represents a bond in this case it being covalent, as you can see the hydrogens are

covalently bonded to the carbons, all these atoms share their valence electrons with each other and

therefor create a strong intramolecular force.

H H

H H

C C

C C

H

H

H Attraction + H

Repulsion -

e

e

p

p

A carbon double bondElectron – electron, proton – proton interactions are repulsive, and proton – electron interactions

are attractive, this is what keeps the lattice structure so tight and strong.

Ethylene is a colorless, flammable gas, that has a musk-like odour, it is responsible for the ripening

of fruit, it is also the backbone of the petrochemical industry because it is so involved.

Most ethylene is converted/derivatized into thermoplastic and used in every day applications, the

production of it is when crude oil is put through a catalytic cracker, and the fraction coming out is

ethylene.

Here are some examples of day to day products that need ethylene:

Reference –

ETHYLENE, 7activestudio, https://www.youtube.com/watch?v=jpitvOxnM4A

√ Production of Ethylene | Production of Materials | Chemistry- itutor.com,

https://www.youtube.com/watch?v=EqvkVu1YD3I

-Metallic Structure

Metal structures contain only metal ions, the electrostatic attraction in these metals is known as

metallic bonds. The ions are arranged side by side in a repeating pattern, the free floating electrons

act like a glue to hold the structure in place, the electrostatic force is strong and this is why metals

are good conductors of heat and electricity.

They have high boiling and melting points because it is very hard to break these bonds.

The seas of electrons allow the metal to be very ductile and malleable, meaning it can stretch and

mould into different shapes because when a force is applied the sheets of metal are able to roll over

each other.

I have set up an example with copper, Cu to have more of an understanding of what happens with

metallic structures.

The ripening of fruit.

Plastic bottles.

Some adhesives.The lines represent the movement of the sea electrons, here we can see that the electrons orbit the

nucleus and are moving rapidly these bonds between electrons and protons are metallic and

attractive, this gives the metal its malleability.

Data

Qualitative Quantitative

Copper (Cu) The electrons are what keep

the ions so tightly packed,

acting as a glue, and moving

rapidly to allow it to be

malleable and ductile.

The 29 electrons that attract

the 29 protons from a

metallic bond and create a

sea of electrons when it

reacts with more copper

atoms.

Because metals are good conductors of heat and electricity they are very useful to us, and with them

also being malleable they cane be turned into wires, jewellery, pots, pans, and many other day to

day tools we use.

Copper is the best conductor of electricity that is why its main production is for wires and in

generators, vehicle radiators, and even inside mobile phone circuit boards.

Here are some examples of appliances that use copper:

Cu+

-

-

-

-

-

-

-

- -

-

-

- -

-

Cu+

Cu+ Cu+

Cu+ Cu+

Cu+

Cu+

Cu+

Cu+

Cu+

Cu+

Cu+

Copper pipes for plumbing.

Copper cutlery.

Copper hinges.

-Not drawn to scale.Reference –

BBC, Bite size, Metallic Structure and Bonding,

https://www.bbc.co.uk/bitesize/guides/z9m6v9q/revision/1

Chemistry LibreTexts, Metallic Structures, Last updated Aug 16, 2020,

https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Modules_and_Websites_(Inorganic_

Chemistry)/Crystal_Lattices/Lattice_Basics/Metallic_Structures

Copper jewellery.

Copper kettle.

Formal Assessment Task Notification Year 11 Chemistry
Context
Students use knowledge obtained from the study of the periodic table to examine trends and patterns that exist between chemical elements and atoms in order to discover that
fundamental particles, and their role in the structure of an atom, give all chemicals their properties.

Task number: 1

Weighting: 25%

Outcomes assessed A student: § designs and evaluates investigations in order to obtain primary and secondary data and information CH11/12-2 § selects and processes appropriate qualitative and quantitative data and information using a range of appropriate media CH11/12-4 § communicates scientific understanding using suitable language and terminology for a specific audience or purpose CH11/12-7 § explores the properties and trends in the physical, structural and chemical aspects of matter CH11-8

 

Task number: 1

Weighting: 25%

Nature of the task Students will research the major types of chemical structures and present a series of drawings, either physical or digital, to show the features of the major types, including: § ionic networks § covalent networks (including diamond and silicon dioxide) § covalent molecular § metallic structure Students: § make reference to factors affecting these structures, eg intramolecular bonding and polarity § annotate or label each structure § provide an analysis of the drawing and its suitability § provide named examples of each chemical structure § provide a reference list using approved referencing style

Marking guidelines