Energy and Environment Exam 1

What is matter?

Anything that occupies space and has mass.

What are the three phases of matter?

Solid, liquid, and gas.

What is a heterogeneous mixture?

A combination of solids, liquids, or gases that are not uniformly distributed throughout the substance.

What is a homogeneous mixture?

A single-phase combination with uniform distribution; often called a solution.

What is an atom?

The smallest unit of an element that can exist as a stable, independent entity

What is an element?

A pure substance containing only one type of atom

What is a chemical formula?

A symbolic way to represent the elements and atomic ratio in a compound.

What is a chemical symbol?

A one- or two-letter abbreviation for an element.

What does the atomic number represent?

The number of protons in the nucleus of an atom.

How do you find the number of neutrons?

Atomic mass − atomic number.

For a neutral atom, what equals the number of protons?

The number of electrons

What are properties of metals?

Shiny, solid at room temperature, malleable, and good conductors of heat and electricity.

What is respiration?

The process of converting food into CO₂, water, and energy in the body.

What is photosynthesis?

The process where plants use light, water, and CO₂ to make glucose and release oxygen.

What are the layers of the atmosphere (from Earth outward)?

Troposphere, stratosphere, mesosphere, thermosphere, exosphere.

Where do humans live in the atmosphere?

The troposphere (contains ~75% of the atmosphere).

Why does pressure decrease with altitude?

There are fewer gas molecules at higher levels.

What are the main components of air?

Nitrogen (78%), oxygen (21%), argon, CO₂, and water vapor.

What is a molecular compound?

A pure substance with two or more nonmetal atoms.

How are molecular compounds named?

Use prefixes for atom count (di-, tri-, tetra-) and add “-ide” to the second element.

Why is CO called carbon monoxide, not monocarbon monoxide?

“Mono” is not used for the first element when only one atom is present.

What does carbon monoxide do?

Prevents hemoglobin from carrying oxygen; can be deadly.

What are symptoms of ozone exposure?

Coughing, chest pain, sneezing, reduced lung function.

What are health effects of sulfur dioxide?

Forms acid in lungs; affects elderly and those with asthma.

What is nitrogen dioxide known for?

Brown color, component of smog, forms acid in lungs

What are sources of lead pollution?

Metal processing, batteries, incinerators, plumbing materials.

What is particulate matter (PM)?

A mix of tiny solids/liquids in air; smaller particles are more harmful.

What is PM2.5?

Fine particulate matter with diameter ≤ 2.5 µm, linked to serious health risks.

Who sets healthy pollutant limits?

WHO and EPA.

What is considered “good” air quality on the AQI scale?

AQI 0–50.

What does orange on the AQI mean?

Unhealthy for sensitive groups.

What is the EPA standard for PM2.5?

9.0 µg/m³ annually.

What does a catalytic converter do?

Converts CO, hydrocarbons, and NOx into CO₂, water, and N₂.

What is “bad ozone”?

Ground-level ozone from pollution; causes respiratory issues.

What causes most pollutants?

Natural processes and human activities (e.g., combustion, industry).

what is an electromagnetic wave?

A wave of oscillating electric and magnetic fields that carries energy.

What is the electromagnetic spectrum (lowest to highest energy)?

Radio → Microwave → Infrared → Visible → UV → X-ray → Gamma ray.

What is the equation relating wavelength and frequency?

λ × ν = c.

What is the equation for energy of radiation?

E = h × ν

What does Planck’s constant (h) equal?

6.626 × 10⁻³⁴ J·s.

Which type of radiation has the shortest wavelength and highest energy?

Gamma rays

Which type of visible light is most energetic?

Violet (400 nm).

Which type is least energetic?

Red (700 nm).

What are valence electrons?

Electrons in the outermost shell that form bonds

What is a single bond?

Two shared electrons.

What is a double bond?

Four shared electrons.

What is the octet rule?

Atoms form bonds to have eight valence electrons.

What is “good ozone”?

Stratospheric ozone that absorbs UV radiation.

What are Dobson Units (DU)?

Units to measure ozone thickness (100 DU = 1 mm of pure ozone)

What ozone value indicates a hole?

Below 100 DU.

Where is the ozone hole located?

Over Antarctica.

When is the ozone hole largest?

Southern Hemisphere spring (September–October).

Why does the ozone hole form?

Polar stratospheric clouds and chlorine radicals destroy ozone.

Why are UVB and UVC absorbed?

They have enough energy to break ozone molecules apart.

What are CFCs?

Chlorofluorocarbons—compounds that release chlorine radicals destroying ozone.

What was the Montreal Protocol?

A 1987 international agreement to phase out CFCs.

What are HCFCs?

Partial replacements for CFCs; still ozone-depleting.

What are HFCs?

Do not harm ozone but contribute to global warming.

What are HFOs?

Newer replacements with low global warming potential and no ozone depletion.

How can UV radiation damage health?

Causes DNA mutations, skin cancer, eye damage, and immune suppression.

What are inorganic sunscreens?

Contain zinc oxide or titanium dioxide; reflect UV radiation.

What are organic sunscreens?

Contain carbon-based molecules that absorb UV radiation

Why does Earth have livable temperatures?

Earth’s atmosphere traps heat from the Sun through the greenhouse effect, keeping temperatures warm enough to sustain life — unlike other planets.

Why is Venus hotter than expected?

Although Venus should be about 100°C based on distance from the Sun, it’s actually ~450°C due to its thick CO₂ atmosphere that traps heat.

Energy balance on Earth

Life depends on a delicate balance between incoming solar energy and outgoing heat. Too much trapped heat causes warming; too little causes freezing.

What happens to 100% of the Sun’s incoming energy?

• 23% absorbed by atmosphere

• 25% reflected by atmosphere

• 6% reflected by Earth’s surface

• 46% absorbed by Earth’s surface

How Earth emits and absorbs energy

Of the 46% absorbed by Earth’s surface:

• 9% is emitted back into space

• 37% absorbed by the atmosphere (total = 46%)

What is albedo?

The fraction of incoming solar radiation reflected back into space by a surface. High albedo = more reflective (ice); low albedo = absorbs heat (oceans, soil).

What is the greenhouse effect?

The natural process where gases like water vapor and CO₂ trap some of the Sun’s heat, keeping Earth’s surface warm enough for life.

How have humans changed the greenhouse effect?

Burning fossil fuels and deforestation have increased greenhouse gas concentrations, amplifying the effect and causing global warming.

What activities increase greenhouse gases?

• Burning fossil fuels for energy, heat, and transport

• Deforestation and land-use changes

• Agriculture (livestock and fertilizers)

• Industrial processes (cement, chemicals)

• Fluorinated gases from equipment/products

Examples of greenhouse gases

• Major: H₂O, CO₂, CH₄, N₂O

• Fluorinated: HFCs, PFCs, SF₆

• Others: O₃ (ozone)

Why must we consider water vapor with CO₂?

Water vapor is the most abundant and potent greenhouse gas, so CO₂’s effects must be understood relative to water vapor’s influence.

Spectrum of solar radiation

The Sun’s radiation spans 240 nm to 2.5 μm; ozone (O₃) and oxygen (O₂) absorb UVB and UVC light, protecting Earth’s surface.

Why are some gases greenhouse gases?

Molecules that are asymmetrical (based on Lewis structures) or have a dipole moment can vibrate/rotate to absorb infrared energy — making them greenhouse gases.

What is a dipole moment?

A measure of electric charge difference within a molecule; molecules with dipole moments can absorb infrared radiation and trap heat.

How do CO₂ and CH₄ compare as greenhouse gases

Methane (CH₄) is 29 times more potent than CO₂ but less abundant; both significantly contribute to global warming.

What is the carbon cycle?

The movement of carbon among the atmosphere, plants, oceans, and rocks. CO₂ is absorbed by plants, stored in oceans, and released by burning fuels or decay.

What are examples of carbon sources and sinks?

• Sources: Fossil fuels, deforestation, agriculture, air travel.

• Sinks: Oceans, plants, soil carbon, reforestation.

Example – CO₂ from deforestation vs. flights

• 200 tonnes CO₂/hectare × 500 hectares = 100,000 tonnes CO₂

• 100,000 ÷ 150 = ~667 transatlantic flights equivalent

Why do cows and landfills emit CH₄?

Through anaerobic fermentation — microorganisms break down organic matter without oxygen, producing methane (CH₄) and water.

What is anaerobic fermentation?

A process where organisms convert sugars into energy (ATP), CO₂, and other products like lactic acid or methane, without using oxygen.

Example – switching to solar

Switching to solar reduces CO₂ emissions by ~80%.
Example: 5 tonnes CO₂/year × 0.80 = 4 tonnes saved = ~800 CO₂ savings ≈ 40,000 trees.

What are the main CO₂-emitting sectors?

• Electricity & heat production

• Transportation

• Manufacturing & industry

• Buildings (especially concrete and cement production)

Why is CO₂ more concentrated in the Northern Hemisphere?

The Northern Hemisphere has more land, industry, and population — leading to higher emissions and less ocean absorption than the Southern Hemisphere.