Atomic Structure, Chemical Bonding, and Gas Laws

Comprehensive flashcards covering atomic structure, electronic configurations, periodic trends, bonding, molecular shapes, and gas laws based on lecture transcripts.

Where is nearly all of an atom's mass concentrated?

In a tiny region in the centre of the atom called the nucleus.

What two types of particles make up the nucleons in the nucleus?

Protons and Neutrons.

What are the regions of space outside the nucleus where electrons move called?

Orbitals.

What is the collective term for the arrangement of electrons in an atom?

Electronic structure or electronic configuration.

What are the maximum electron capacities for the first and second principal quantum shells?

Shell 1 can hold up to $2$ electrons; Shell 2 can hold up to $8$ electrons.

What are the four letters used to distinguish subshells?

$s$, $p$, $d$, and $f$.

What is the maximum number of electrons allowed in $s$, $p$, $d$, and $f$ subshells?

$s=2e$, $p=6e$, $d=10e$, and $f=14e$.

According to the Aufbau Principle, in what order do electrons fill orbitals?

Electrons fill the orbitals of lowest energy before occupying higher energy levels.

What is an atomic orbital?

A region of space around the nucleus of an atom that can be occupied by one or two electrons.

How many orbitals are contained in the $s$, $p$, and $d$ subshells?

$s$ has $1$ orbital, $p$ has $3$ orbitals, and $d$ has $5$ orbitals.

What does the Pauli Exclusion Principle state regarding atomic orbitals?

An atomic orbital can hold a maximum of $2e$ and they must have opposite spins.

What is Hund's Rule?

Degenerate orbitals are filled singly with the same spin before being doubly occupied.

How are isotopes defined?

Atoms that have the same number of protons (atomic number) but a different number of neutrons (mass number).

Which isotope of Carbon is mentioned as being unstable and radioactive?

Carbon-14 (containing $8$ neutrons and $6$ protons).

What is the difference between qualitative and quantitative analysis in spectroscopy?

Qualitative analysis is used for identification of a material, while quantitative analysis (spectrometric techniques) is for determining composition or concentration.

In a flame test, what color does Lithium ($Li^+$) produce?

Red.

In a flame test, what color does Potassium ($K^+$) produce?

Lilac.

In a flame test, what color does Barium ($Ba^{+2}$) produce?

Apple green.

What are the two main problems with the flame test?

1. Sodium impurities can hide other colors with their intense yellow. 2. Describing colors with words is subjective.

What causes the characteristic colors in a flame test?

Electron transition: electrons absorb energy to move to an excited state and then release energy as visible light when returning to the ground state.

Who invented the mass spectrometer in 1919?

Francis Aston.

On what basis are ions separated in a mass spectrometer?

According to their mass-to-charge ($m/z$) ratios.

What does Atomic Emission Spectroscopy (AES) measure?

Light emitted from excited atoms as they return to the ground state.

What is the principal of Atomic Absorption Spectroscopy (AAS)?

It measures the absorption of radiations by ground state gaseous metal atoms.

Define first ionisation energy ($\text{I.E.}$).

The energy required to remove one electron from each atom in a mole of gaseous atoms to form a mole of gaseous $1+$ ions ($X_{(g)} \rightarrow X^+_{(g)} + e$).

What three factors influence ionisation energies?

1. The size of the nuclear charge. 2. Distance of outer electrons from the nucleus. 3. Shielding effect of inner electrons.

Why does ionisation energy generally decrease down a group?

Because the distance between the nucleus and the outer electron increases and the shielding by complete inner shells increases, outweighing the increased nuclear charge.

What is the shielding effect?

When full inner shells of electrons prevent the full nuclear charge from being felt by the outer electrons due to electron-electron repulsion.

What is the definition of electronegativity ($\text{EN}$)?

The ability of an atom to attract electrons towards itself.

How is effective nuclear charge calculated?

$\text{Effective Nuclear Charge} = \text{Number of protons in the nucleus} - \text{Number of total inner shell electrons}$.

What trend does atomic radius follow across a period?

It decreases because the number of occupied shells remains constant while the effective nuclear charge increases, pulling valence electrons more strongly.

What does the term 'isoelectronic' mean?

Atoms and ions that have the same electron configuration.

What is an empirical formula?

The simplest whole number ratio of elements in a compound.

What are the characteristics of ionic compounds regarding electrical conductivity?

They do not conduct electricity when solid because ions are tightly bound, but they do conduct when molten or in aqueous solution as ions are free to move.

What is the definition of Allotropes?

Different arrangements of atoms of the same element that give them different physical forms (e.g., Diamond and Graphite for Carbon).

Why is Diamond a non-conductor of electricity?

It does not contain any charged particles (electrons or ions) that are free to move.

Why can Graphite conduct electricity?

It contains delocalised electrons that are able to move within the layers of its structure.

What is Avogadro's constant ($N_A$)?

$6.02 \times 10^{23}$ particles per mole.

According to VSEPR theory, what is the bond angle for a tetrahedral molecule like $CH_4$?

$$109.5^{\text{o}}$$

What is the bond angle in a V-shaped molecule like water ($H_2O$)?

$$104.5^{\text{o}}$$

What are the three types of intermolecular forces mentioned?

1. Dispersion (Van der Waals) forces. 2. Permanent dipole-dipole forces. 3. Hydrogen bonding.

Between which atoms does hydrogen bonding specifically occur?

Between hydrogen and highly electronegative atoms: Oxygen ($O$), Nitrogen ($N$), or Fluorine ($F$).

State Boyle's Law.

For a fixed amount of gas at constant temperature, pressure is inversely proportional to volume ($P_1V_1 = P_2V_2$).

State Charles's Law.

For a fixed amount of gas at constant pressure, volume is directly proportional to the absolute temperature in Kelvin ($\frac{V_1}{T_1} = \frac{V_2}{T_2}$).

What is the molar volume of any gas at STP ($100\text{\thinspace kPa}, 0\text{\thinspace }^{\text{o}}\text{C}$)?

$22.7\text{\thinspace dm}^3$ (or $L$).

What is the Ideal Gas Law equation?

$PV = nRT$.

What is the value and unit of the universal gas constant ($R$) used in the notes?

$8.31\text{\thinspace J\thinspace K}^{-1}\text{\thinspace mol}^{-1}$.