Chemistry Gr 12 Unit 1

order of the electromagnetic spectrum by longest to shortest wavelength

radio, microwave, infrared, visible, UV, X-ray, gamma ray

What is frequency

How often. Measured in Hz or S^-1

What is wavelength

Colour. Measured in distance (usually nm)

What is amplitude

“intensity”, “brightness”, “loudness”, “height”

order of colours by wavelength

ROYGBIV

What happens when wavelength goes down?

Energy goes up

nm in m

1x10^-9

order of metric

metre, milli (-3), micro (-6), nano (-9), pico (-12)

What was predicted to happen to hydrogen when it was heated up

It should have emitted white light bc electrons can absorb all wavelenths of energy so they should’ve radiated off all as well.

what was observed when the hydrogen was heated

In the end the hydrogen emitted a pink light. When the light was shown through a prism instead of there being all the colours, there were only a specific colours of red, green, blue and violet. This demonstrated that only specific wavelengths could be absorbed by the Hydrogen atom. (staircase model)

what specific colours were seen after heating hydrogen

656nm (red, 3 → 2), 486nm (green, 4 → 2), 434nm (blue, 5 → 2), 410nm (violet, 6 → 2)

What is the emission spectrum

The specific wavelengths that are produced when an electron falls from one ring to another. It has black spaces and coloured lines.

What is the absorption spectrum

The colours absorbed by the element. This is seen as the opposite of the emission spectrum as the specific quantities that release a specific light can’t be on the absorbtion spectrum as it would move the elctron onto the next ring. The absorbtion spectrum has black lines and coloured spaces.

what is the lyman series

Calculation of when electrons fall to the first ring. Produces UV light.

what is the balmer series

calculation of when electrons fall to the second ring

what is the paschen series

Calculation of when electrons fall to the third ring. Produced infrared results

What is the Aufbau principle?

The Aufbau principle states that electrons fill the lowest energy levels first before moving to higher energy levels in an atom.

What is the Pauli Exclusion Principle?

an orbital can have a max of 2 electrons and they must have opposite spins

What is Hund's rule?

Hund's rule states that when filling orbitals of equal energy, electrons will occupy separate orbitals

Energy level diagrams

bottom to top

What is the shape of s orbitals?

S orbitals have a spherical shape that gets bigger for every added number

What is the shape of p orbitals?

8s, infinity, and rotated 8 getting progressively bigger for every added number

What is the shape of d orbitals?

4 leaf clover, rotated 5 times and gets bigger for each number

What is the shape of f orbitals?

a flower with 6 petals, rotated 7 times, bigger for each number

what are the valence electrons in quantum model

s+p of highest quantum number

electron configuration

1s2 2s2 2p6 3s2 3p6 4s2 3d10 …

short hand electron config.

[noble gas] 2s2 2p6 3s2 3p6 4s2 3d10 …

short hand electron configuration for a noble gas

use previous noble gas and full config

orbital diagram

[noble gas] horizontal lines

what is an anion

an ion with a negative charge bc it has gained an electron

what is a cation

an ion with a positive charge bc it has lost an electron

how to draw a cation as an orbital diagram

cross out the valence electrons that are removed

how to draw an anion as an orbital diagram

cross out the previous number and replace it with the added one

which elements have electrons that get promoted

copper (Cu), silver (Ag), and Gold (Au)

what does it mean for electrons to get promoted

one of the valence s electrons moves to d orbital to fill it in the ground state

What does the term "ferromagnetic" mean?

Ferromagnetic refers to materials that have a strong attraction to magnetic fields, allowing them to become magnetized even when the magnetic field is removed.

What does the term "paramagnetic" mean?

Paramagnetic refers to a substance or material that is weakly attracted to a magnetic field due to the presence of unpaired electrons. These elements magnetism disappears when the field is removed

What does the term "diamagnetic" refer to?

Diamagnetic is a property of materials that are not attracted to a magnetic field and have no permanent magnetic moment.

What are quantum numbers

a “postal code” indicating the location or position of an electron

what is the order of the parts of the quantum number of an electron

n, l, ml, ms

what is the principal quantum number

n (number of energy levels)

what are the possible numbers for n

1 → infinite

what is the secondary quantum number

L (orbital shape)

what are the possible numbers for L

0 → n-1

what is the magnetic quantum number

ml (orbital orientation)

what are the possible numbers for ml

-L → +L

What is the spin quantum number

ms (electron spin)

what are the possible numbers for ms

-1/2 or +1/2

what is always important to remember when stating the ms

the positive/negative sign

What are the factors that affect atomic radius that must me mentioned in every explaination

Principal quantum number(n) and effective nuclear charge (Z_eff)

what is the biggest factor in atomic radius

principal quantum number

as n increases what happens to atomic radius

it increases

as Z_eff increases what happens to atomic radius

it decreases

what is the definition of atomic radius

the distance between the nuclei of 2 adjacent atoms

How to caluclate the effective nuclear charge

atomic number (z) - shielding electrons (non valence electrons) (s)

What happens if an electron is added to create a anion

Since the electrons repel each other, the resulting anion has a larger AR

what is electron affinity

the energy given off when an electron is added to an atom

what is electronegativity

the measure of the electron attracting ability of an atom

What is ionization energy

the energy required to remove an electron from an atom

as n increases what happens to the ionization energy

IE decreases

as Z_eff increases what happens to the ionization energy

IE increases

Where should we look for exceptions in the ionization energies

B, Al, O, S

Why does the ionization energy decrease from Be to B and Mg to Al?

The ionization energy decreases from Be to B and Mg to Al due to the shielding effect. The shielding effect occurs when inner electrons (1s, 2s namely) shield the outermost electron from the full positive charge of the nucleus, reducing the ionization energy. Therefore, the ionization energy decreases.

Why is there a drop in ionization energy between N and O and P and S?

The ionization energy is reduced due to the repulsion between the paired electrons in the 2p/3p, making the electron easier to remove.

what is the term for atoms with common electron configs

isoelectronic

what does shell mean

the n value / principal quantum number

what does subshell mean

the orbital type (l) (s,p,d,f)

what does orbital mean

a specific region where a max of 2 electrons can be found

intermolecular forces

The forces of attraction between molecules, determining their physical properties. Examples include hydrogen bonding, dipole-dipole interactions, and London dispersion forces.

intramolecular forces

Forces that hold atoms together within a molecule. They include covalent bonds, which involve the sharing of electrons, and ionic bonds, which involve the transfer of electrons between atoms. These forces determine the structure and properties of a molecule.

If atoms in a compound have an electronegativity difference of >=1.7 what does that mean

it means that the compound is more ionic

If atoms in a compound have an electronegativity difference of <1.7 what does that mean

It means the compound is more covalent

what are ionic bonds

Chemical bonds formed between atoms by the transfer of electrons. They occur between a metal and a non-metal, resulting in the formation of ions with opposite charges.

What is the ionic crystal lattice

A 3D arrangement of positive and negative ions held together by electrostatic forces. It forms repeating unit cells, creating a stable structure.

In an ionic crystal what is larger anions or cations

anions

What is lattice energy

The energy required to break apart one mole of an ionic solid into its constituent ions in the gas phase. It measures the strength of the ionic bond in the solid.

What are factors that increase lattice energy

Primary: high charge and low AR

Secondary: high boiling point, high melting point, conduct electricity in (aq), (g), (l) states

When covalent bonds have an EN of 0-0.5 what can be said about the bond type

it is pure covalent

How to calculate formal charge

valence electrons (VE) - non bonding electron (NB) - Bonds

Will the octet rule always be followed?

No, while CNOF tends to follow it, as you move down the periodic table, it becomes more likely.

What is a coordinate covalent bond

A coordinate covalent bond is a type of chemical bond that is formed when both electrons in the shared pair come from the same atom

What is an expanded valence

when the central element in an atom has a valence shell greater than 8

What is an reduced valence

when the central element in an atom has a valence shell less than 8

What is the process used to calculate the lewis structure

Need:

1. calculate the needed electrons

   Have:

2. calculate the number of electrons the elements already have

3. add/subtract the charge

   For bonds:

4. Need-Have

   For electrons:

5. Have - Bonds(2)

   Drawing:

6. Lowest electronegative element in the middle

7. draw bonds

8. place electrons going from outside to inside

9. put square brackets and charge

can fluorine make double bonds

No

When is a structure considered a resonance structure

when a double bond can be drawn with the double bond in 2+ locations without changing the arrangement of the atoms.

What are resonance hybrids

Resonance hybrids are multiple Lewis structures that represent a molecule's real structure. They are formed when a molecule can be represented by more than one valid Lewis structure.

What must be included in a lewis structure of resonance hybrids

the arrows showing the movement of the double bonds

What can be said about the electrons in the double bond of a resonance structure

they are delocalized

what does it mean for an the electrons in a bond to be delocalized

it means they are shared over all the bonds

What is molecular polarity

the distribution of charge on the entire molecule

What does polarity affect

many physical and chemical properties such as it’s state

physical properties

A physical property is a characteristic of matter that is not associated with a change in its chemical composition. Familiar examples of physical properties include density, color, hardness, melting and boiling points, and electrical conductivity.

chemical properties

A chemical property is any of a material's properties that becomes evident during, or after, a chemical reaction

Examples of chemical properties include flammability, toxicity, acidity, reactivity

how to check polarity

1. check bond polarity

2. use the shape to see the symmetry of polarity

3. note the effect of lone electron pairs on the central atom

4. indicate direction of polarity using arrow pointing to the more electronegative end

what is hydrogen bonding

Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom, covalently bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine, is attracted to another electronegative atom in a different molecule. This attraction results in a relatively strong bond between the molecules.

what is dipole-dipole bonding

Dipole-dipole bonding is a type of intermolecular force that occurs between polar molecules. It results from the attraction between the positive end (or pole) of one molecule, which has a partial positive charge, and the negative end (or pole) of another molecule, which has a partial negative charge

what is ion-dipole bonding

Ion-dipole bonding is a type of chemical interaction between an ion (charged particle) and a polar molecule. It occurs when the positive or negative charge of the ion attracts the partial charges of the polar molecule.

what is ion-induced dipole bonding

Ion-induced dipole bonding is a type of intermolecular interaction that occurs when a charged ion induces a temporary dipole moment in a nearby neutral molecule or atom.

what is dipole-induced dipole bonding

Dipole-induced dipole bonding occurs when a polar molecule induces a temporary charge on another molecule. For example, the negative side of an HCl molecule will repel the negative electrons of O2 creating temporary positive and negative sides.