Chem Review Exam 2

What happens to photon energy when frequency increases?

Photon energy increases because E = hν.

What is the relationship between wavelength and frequency?

They are inversely proportional: as wavelength increases, frequency decreases.

Which visible light has the highest energy?

Violet light; it has the highest frequency and shortest wavelength in the visible spectrum.

Which visible light has the lowest energy?

Red light; it has the lowest frequency and longest wavelength in the visible spectrum.

What is the equation relating wavelength, frequency, and the speed of light?

c = λν.

What is the equation for photon energy using frequency?

E = hν.

What is the equation for photon energy using wavelength?

E = hc/λ.

What is the speed of light, c?

3.0 × 10⁸ m/s.

What is Planck's constant, h?

6.626 × 10⁻³⁴ J·s.

What does kilo (k) mean in a unit conversion?

Multiply by 10³, or 1,000. For example, 30 kHz = 30,000 Hz.

How do you multiply powers of ten?

Add the exponents: 10ᵃ × 10ᵇ = 10ᵃ⁺ᵇ.

How do you divide powers of ten?

Subtract the exponents: 10ᵃ ÷ 10ᵇ = 10ᵃ⁻ᵇ.

What happens in the photoelectric effect?

Light shines on a material and can eject electrons if each photon has enough energy.

What is threshold frequency?

The minimum frequency needed for photons to eject electrons from a particular material.

What happens if light is below the threshold frequency?

No electrons are ejected, regardless of light intensity.

What does increasing light intensity do in the photoelectric effect?

It increases the number of photons arriving per unit time; above threshold, this can eject more electrons.

Does increasing intensity make each photon more energetic?

No. Photon energy depends on frequency, not intensity.

What experimental observation supports the particle model of light?

The photoelectric effect: electron emission depends on photon frequency reaching a threshold, not just on intensity.

What happens when an electron moves to a higher energy level?

It absorbs energy.

What happens when an electron moves to a lower energy level?

It emits a photon.

What produces a line in an emission spectrum?

An electron drops to a lower energy level and emits a photon of a specific energy and wavelength.

Why does each element have a unique emission spectrum?

Each element has its own allowed electron energy levels and energy differences.

What does an absorption spectrum look like?

A continuous spectrum with dark lines where particular wavelengths have been absorbed.

What does an emission spectrum look like?

Bright lines at particular wavelengths against a dark background.

Why do absorption and emission lines occur at the same wavelengths for an element?

They correspond to the same energy differences between allowed energy levels; absorption is an upward transition and emission is a downward transition.

What is an atomic orbital?

A region of space where there is a high likelihood of finding an electron of a certain energy.

What shape is an s orbital?

Spherical.

How does a 2s orbital compare with a 1s orbital?

Both are spherical, but the 2s orbital is larger.

What happens to atomic radius from left to right across a period?

It generally decreases because effective nuclear charge increases while the number of occupied core shells stays the same.

What does a large jump in successive ionization energies suggest?

The next electron would be removed from a lower, core shell rather than the valence shell.

How do you write a neutral ionic compound's formula?

Choose the smallest whole-number ratio of ions that makes the total charge zero.