The valency of an element is the capacity of the element at which it is able to combine with other atoms of other molecules when it forms chemical compounds or molecules.
Identify the charges on atoms in a compound
The charge of an element is equal to the number of protons minus the number of electrons. The number of protons is equal to the atomic number of the element given in the periodic table. If there are more electrons in a compound then the charge of the compound may be negative and vice versa if there are more protons present.
State that the transition metals can form more than one ion, including examples
Transition metals are metals that have two valence electrons instead of only one. Some examples of transition metals include iron and manganese. Hence, they can form more than one ion as they can transfer 2 electrons. For example, iron commonly forms two different ions.
State the formula and charge on common polyatomic ions
Polyatomic ions are ions with more than one type of atom present with a positive or negative charge. An example would be NO3, this is a polyatomic ion as it has one nitrogen atom and three oxygen ions and it has a negative charge.
Describe the law of conservation of mass
The law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. That is that the mass of the reactants would equal the mass of the products. Therefore, in the process, additional mass is not created and mass is not removed in the reaction.
State the rules to be followed when balancing chemical equations
When balancing the chemical equation, the number of molecules on either side of the equation has to be the same.
Balance chemical equations
The law of conservation of mass states that in a chemical and physical change mass is neither created nor destroyed, thus balancing an equation is crucial to abide by this law. An example to balance an equation is as follows:
O + C → CO2
- This equation is not balanced as there are two Oxygen atoms on the right-hand side and only one on the left.
- Hence, we add an oxygen atom to the left to equalize the two oxygen atoms. we can do so by adding a 2 in front of the oxygen symbol.
- To calculate the number of atoms present, you must multiply the bigger number on the left-hand side by the smaller number on the right hand (if there is no number present on the right, calculate it as 1).
2O + C → CO2
Another Example is as follows:
N2 + H2 → NH3
- First, count the number of atoms on each side
- Then, equalize the number of nitrogen atoms of each side by adding a coefficient on NH3 so it becomes 2NH3
- Lastly, equalize the number of Hydrogen atoms by adding a coefficient on H2 so it becomes 3H2
N2 + 3H2 → 2NH3
Explain Lattice Structure:
A lattice structure is a space-filling unit that has the capabilities to repeat itself along any axis without any gaps between cells. These structures are a solution to weight and energy. These lattices are formed because the ions attract each other and form a pattern with oppositely charged ions next to each other
Define Ionic Bonding
An Ionic bond is a bond in which two atoms share an electrostatic charge. Ionic compounds are neutral compounds made up of positively and negatively charged ions known as cations, and anions respectively.
Ionic compounds usually have high boiling points and are hard and brittle as well.
Describe how ions are formed as a result of electron transfer
An ion is an atom with an electric charge due to the loss or gain of an electron. This occurs as a result of an electron transfer. To calculate a charge of an electron, one has to subtract the number of protons by the number of electrons present in an atom. Hence, if the number of electrons is affected by an electron transfer, the charge is not equal to 0 and hence the ion has a charge.
Describe the process of ionic bonding using scientific terminology
Sodium has one valence electron in its outer shell, whereas Chlorine is missing one valence electron, and so it is transferred to Chlorine to make both atoms stable. After the transfer, they both turn into ions and electrostatic attraction bonds them
Illustrate an ionic bond
Name & write the correct chemical formula of ionic compounds
To write a chemical formula of an ionic compound you must first write the symbol of the cation and an anion along with their charge.
- Split the formula in two between the elements
NaCl = Na|Cl NH4F = NH4|F
- Determine the ions and their charge
- Practice with Salts
NaCl = Na|Cl = Na+|Cl-
Examples of Ionic Compounds
Define Covalent Bonds
A covalent bond is a type of atomic bonding in which if two or more atoms need to fill their outer shell, yet none of them are metals, they can just share electrons.
An example of this is 2 Chlorine atoms (Dichloride). Both chlorine atoms are missing one electron to fill their outer shell completely, and so instead of transferring the atoms, they share electrons. In the end, two electrons are shared between the two, and both atoms have their outer shell filled with each other
Describe how a covalent bond is formed using scientific terminology
The subatomic particles in a chemical compound hold together the molecule especially the attraction between the oppositely charged subatomic particles. In a covalent bond, the electrons are shared which are attracted by both atom’s positively charged nuclei, therefore, the two different molecules are quite strongly bonded through the electrostatic attraction.
Identify differences between single, double, & triple bonds
Two molecules must share a certain amount of molecules to complete their outer shells depending on the valency of the atoms. Thus, single bonds, double bonds, and triples bonds occur where atoms share their respective amount of electrons. The higher the number of electrons shared, the stronger the intermolecular attraction, therefore, triple bonds are the hardest to break whereas single bonds are the easiest to break.
In a single bond, two electrons are shared amongst the atoms. In a double bond, four electrons are shared, in a triple bond, six electrons are shared
Define the term Electrostatic Attraction
Electrostatic attraction is what allows two ions to bond and come together. If the two atoms are neutral, the electrostatic attraction will repel them away from each other. If you have one cation and one anion, the positive and negative charges would attract each other – similar to a magnet
In a covalent bond, the negative charge comes from the electrons of the atoms, and the positive charge comes from the nuclei of the atoms.
Illustrate a covalent bond
- Ideally, use crosses and dots to represent electrons from different elements
- Draw overlapping circles to represent different atoms in a compound
- Draw the crosses and dots in the intersection of these overlapping circles to represent shared electrons, remember they must come in pairs.
- You may wish to plot the remaining electrons on the outer shell for clarity, and the initial atoms for your reference.
- Also, represent the single, double and triple bonds in the written version of the compound. (As shown for hydrogen)
Describe & compare Carbon allotropes (diamond, graphite, graphene & C60 Fullerene)
Diamond is commonly known as the hardest material on earth. It has a durable cage structure with a lot of bonds. Graphite can be found in pencils, and it is bonded in sheets with weak bonds in between, allowing them to slide off each other. Graphene is arranged in a hexagonal lattice and is used as a coating for anti-corrosion. Lastly, C60 Fullerene is a carbon allotrope with bondings that form a ball with pentagonal structures.
Describe & compare simple & giant covalent structures (silicon dioxide and silica)
Simple Covalent Structure:
This is the regular kind of covalent bonding, in which the molecules are bonded together by a shared pair of electrons.
Giant Covalent Structure:
A giant covalent molecular structure is a structure made up of multiple covalent bonds of the same molecules repeated in a 3D lattice structure.
Define “aqueous state”
The term “aqueous state” refers to a solution in which water is the solvent that dissolves the solute (which in this case is Lithium Chloride). If a bond were to conduct electricity in an aqueous or in general in a molten (liquid) state, then it conducts electricity, and since Lithium Chloride conducts electricity, we know that it is an ionic bond. The reason why ions can conduct electricity in water is that the ions are able to move freely from place to place
Describe the metallic bonds using scientific terminology
Solid metals have a lot of atoms arranged in a regular structure and hence creating a giant structure of atoms. These atoms lose their outermost electrons and become cations while sharing their electrons (known as the delocalized electrons) with each other in the metal. This results in electrostatic force between the positive cations and negative electrons, which holds everything together in a regular structure and provides metal with its typical properties. This bond between the metal’s atoms is known as metallic bonding.
Create links between the bonding which occurs in metals and the properties of metals
Strength and MP & BP
The strong electrostatic forces give the metal its strength due to great attraction between the subatomic particles, furthermore, this also increases the MP and BP since greater energy/heat is required to overcome the Intermolecular forces. Therefore, most metals are solid at room temperature and very strong.
Conductivity of electricity and heat:
The delocalized electrons are able to carry the electricity and thermal energy and heat, therefore, metallic structures are good conductors of heat and electricity due to these delocalized electrons which is not found in other nonmetals.
Malleable and ductile:
Despite the strength of metallic structures due to the electrostatic force, metals can still be easily bent or hammered into shapes as well as drawn into wire, this is because the metallic structures are often in a regular pattern and thus layers can be slid over one another and thus they are not as fixed.
Compare and explain the properties of substances resulting from different types of bonding
Differentiate between intermolecular and intramolecular forces of attraction & include examples
These are the bonds that keep the atoms within the molecule close to each other and allow the molecule to exist without it collapsing
These are the bonds that keep molecules from being connected