SCH3U FINAL EXAM REVIEW JAN 2024

look at other knowts for practice these are more so short answers : concepts

S/A: Discuss and explains trends in the periodic table using Zeff / valance structure / radius in your explanation.

Down a group, elements have the same Zeff and valance structure, but have an increasing amount of mainshells. Atoms get larger: This is because each step down a group means the addition of one more mainshell, so valance electrons occupy mainshells further away from the nucleus.

Across a period, elements ahve their valance electrons in the same mainshell as well as the same core configuration. Zeff goes up by one and each element and the number of valancne e also go up by one. Across the table from left to right, Zeff is increasing, so while you are adding both e- and p+, each successive atom has one more p+ pulling on the e-. The added electron's are all in the same mainshell, and the increase in Zeff pulls the electron’s of that mainshell closer and closer to the nucleus, thus the atoms get smaller​

a) Draw the electron dot diagrams for ammonia (NH3) and another for the ammonium ion (NH4+).

b) show al the work and remark on any unique features for the lewis electron dot diagrams for each of the following: CO3 2-, XeF6, BH3

Remember the rules for drawing ionic, covalent and polyatomic ions, as well as notable exceptions

Explain electronegativity and apply the concept to covalent, polar covalent, and ionic bonds and the bonding continuum.

a) Electronegativity is defined as the measure of an atom’s ability to attract e-’s that are part of a chemical to itself, essentially, an atom’s ability to win a tug of war with other atoms over e-. The higher the electronegativity, the more the atom will try and attract electrons.

b) The differences in electronegativity (△EN) can be used to determine whether or not a bond is likely to be covalent or ionic in nature. the largest (△EN) would happen if F - Fr (the elements with the highest and lowest ENs respectively); 4.0-0.7 = 3.3, and the smallest △EN would occur if identical atoms react, (ie Fr - Fr= 0.7 - 0.7), which would equal zero. This gives us the bonding continuum which allows us to predict if a bond is ionic or covalent. If the difference between the EN is less than 1.7 (the midpoint) covalent is assumed, and if it is greater than 1.7, ionic is assumed.

As for polar covalent bonds, they would occur if the (△EN) is between 0.4 and 1.7, and non polar bonds are between 0-0.4.

Ionic vs Covalent bonds: apply the bonding continuum to explain

The differences in electronegativity (△EN) can be used to determine whether or not a bond is likely to be covalent or ionic in nature. the largest (△EN) would happen if F - Fr (the elements with the highest and lowest ENs respectively); 4.0-0.7 = 3.3, and the smallest △EN would occur if identical atoms react, (ie Fr - Fr= 0.7 - 0.7), which would equal zero. This gives us the bonding continuum which allows us to predict if a bond is ionic or covalent. If the difference between the EN is less than 1.7 (the midpoint) covalent is assumed, and if it is greater than 1.7, ionic is assumed.

Ionic bonding: forms between a metal and non-metal; involve the transfer of electrons from one atom to the other; forms two oppositely charged ions which are electrostatically attracted to each other and form a crystal lattice structure; very strong, high BP, greater radius = weaker ionic bond, greater charge = stronger ionic bond

Covalent bonding: involves the sharing of electrons by two non-metal atoms to achieve a stable octet; very strong, high melting points, more e- shared stronger bond..

Polarity: use the concept of electronegativity to explain how a bond is polar. How is it possible that a molecule with polar bonds can be a non-polar molecule… KNOW POLAR MOLECULES VS NON POLAR MOLECULES

Naming and writing balanced chem eq, ID type of run

using a solubility curve

complete chemical, total ionic, and net ionic eq

detailed explanation of why things dissolve?

Dissolving is when a solute is placed in a solvent and it looks like it disappeared. The solute is not gone, it has simply broken up into smaller pieces and has been distributed throughout the solvent. the process of dissolving is dependent on the interactions between particles of the solvent and the solute. A compound is soluble in a particular liquid if it dissolves in that liquid and insoluble if it does not dissolve in the liquid.

strong vs weak acids / concentrated vs dilute solutions

Concentrated solutions have large quantity of solute in solution while Dilute solutions have a small quantity of the material making up the solution present. 

Strong means it ionizes/dissociates completely (100%) in solution, weak only partially (<50%)

the difference between a concentrated weak acid and a diluted strong acid is that one is more danger. strong acids ionize completely, even if it is diluted, whereas weak acids partially ionize even when concentrated. strong acids will release all of their H+ ions into solution unlike weak acids which only release less than 50% of their H+ ions despite the fact it is more concentrated. the H+ ions are the dangerous part, so strong acids like HBr and HI, even when dilute are more dangerous compared to a weak acid like vinegar (acetic acid).;

mole relationships

determining empirical, molecular formula given composition

determining a limiting reagent, amount of excess and percentage yield

dilution eq

gas law eq