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What is an emission spectrum?
A set of discrete wavelengths emitted when electrons fall from higher to lower energy levels.
What is an absorption spectrum?
A pattern of dark lines in a continuous spectrum caused by electrons absorbing specific wavelengths to move to higher energy levels.
How does the hydrogen emission spectrum provide evidence for energy levels?
It shows distinct spectral lines corresponding to specific electron transitions, proving that energy levels are quantized.
What does the convergence of spectral lines at higher energies indicate?
It represents ionization energy, where the electron completely escapes from the atom.
What are the highest and lowest energy shells involved in electron transitions?
The highest energy shell (n → ∞) corresponds to ionization, while the lowest is n = 1.
What types of light are emitted depending on the electron transition?
n = ∞ to n = 1 → Ultraviolet (Lyman series) n ≥ 3 to n = 2 → Visible light (Balmer series) n ≥ 4 to n = 3 → Infrared (Paschen series)
How are the melting and boiling points of ionic compounds?
They are high due to strong electrostatic forces between oppositely charged ions.
Can covalent compounds conduct electricity?
No, because they do not have free-moving charged particles.
What determines if an ionic compound is soluble in water?
It dissolves if hydration enthalpy is greater than lattice enthalpy.
Why do covalent compounds have lower melting and boiling points?
Because they have weak intermolecular forces rather than strong bonds between molecules.
What type of structure do ionic compounds form?
A giant lattice structure with repeating positive and negative ions.
How do covalent compounds behave in solid form?
They are usually soft and brittle due to weak intermolecular forces.
How do isotopes of the same element differ?
They have different numbers of neutrons but the same number of protons and electrons.
Do isotopes affect the chemical properties of an element?
No, because chemical properties depend on electron configuration, which remains the same.
How does neutron count affect isotope stability?
Too many or too few neutrons can make an isotope unstable, leading to radioactive decay.
What happens during hydration enthalpy?
Gaseous ions dissolve in water, releasing energy as they form hydrated ions.
Which ions have the most exothermic hydration enthalpy?
Small and highly charged ions.
What causes partial charges (δ+ and δ−) in a molecule?
Differences in electronegativity create an uneven distribution of electron density.
How do you determine if a molecule is polar?
Consider bond polarity and molecular symmetry—if dipoles don’t cancel, the molecule is polar.
What makes a substance paramagnetic?
The presence of unpaired electrons, which cause attraction to a magnetic field.
When is a substance diamagnetic?
When all electrons are paired, causing it to be repelled by a magnetic field.
What happens during electron affinity?
An atom in the gas phase gains an electron, releasing energy.
Which group has the most exothermic electron affinity?
Halogens (Group 17), as they need just one more electron to complete their octet.
What does lattice enthalpy measure?
The energy needed to break one mole of an ionic compound into its gaseous ions.
How do charge and ion size affect lattice enthalpy?
Higher charge and smaller ions increase lattice enthalpy due to stronger electrostatic forces.
What happens during electrolysis?
Electricity forces a non-spontaneous reaction, breaking an ionic compound into its elements.
Where do cations move during electrolysis?
To the cathode (negative electrode), where they gain electrons (reduction).
What is produced at the anode during electrolysis?
The anion from the electrolyte.
What is produced at the cathode during electrolysis?
The cation from the electrolyte.
Why do some ionic compounds dissolve in water while others do not?
If hydration enthalpy outweighs lattice enthalpy, the compound dissolves.
How does bond order affect bond length and strength?
Higher bond order leads to shorter and stronger bonds.
Which bond is the longest: single, double, or triple?
Single.
Which bond is the strongest: single, double, or triple?
Triple.
What determines electron domain geometry?
The total number of bonding and lone pairs around the central atom.
What are the possible electron domain geometries?
Linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral.
What counts as an electron domain?
Any region of electron density, including bonding pairs and lone pairs.
How many electron domains does a tetrahedral molecule have?
Four.
How does molecular geometry differ from electron domain geometry?
Molecular geometry considers only bonding pairs, while electron domain geometry includes lone pairs.
How do lone pairs affect bond angles?
They repel bonding pairs more strongly, decreasing bond angles.
What is the shape and bond angle of a molecule with two electron domains?
Linear, 180°.
What is the shape and bond angle of a molecule with three electron domains and no lone pairs?
Trigonal planar, 120°.
What is the shape and bond angle of a molecule with three electron domains and one lone pair?
Bent (angular), <120°.
What is the shape and bond angle of a molecule with four electron domains and no lone pairs?
Tetrahedral, 109.5°.
What is the shape and bond angle of a molecule with four electron domains and one lone pair?
Trigonal pyramidal, <109.5°.
What is the shape and bond angle of a molecule with four electron domains and two lone pairs?
Bent (angular), <109.5°
