Comprehensive Science Review: Energy, Matter, Circuits, and the Periodic Table

Flashcards covering energy efficiency, solutions, density, electrical circuits, subatomic particles, and periodic table trends.

What is the definition of energy?

Energy is the ability to move things and cause change.

What are the three main types of potential energy described in the notes?

Chemical potential energy (stored in chemicals like food), gravitational potential energy (stored when lifting something up), and elastic potential energy (stored when stretching something like a rubber band).

What does the Law of Conservation of Energy state?

Energy cannot be created or destroyed, only transformed from one form to another.

What is the formula used to calculate energy efficiency?

$$\text{Energy efficiency} = \frac{\text{Useful energy output}}{\text{Total energy input}} \times 100\%$$

What are the typical energy efficiency percentages for incandescent, fluorescent, and LED lightbulbs?

Incandescent bulbs are $5\text{--}10\%$ efficient, fluorescent bulbs are $\sim 20\text{--}25\%$ efficient, and LED bulbs are $85\text{--}90\%$ efficient.

How much electricity is required for an incandescent bulb ($10\%$ efficiency) to produce $10\,W$ of light power?

$$\text{Electricity} = \frac{10\,W}{10\%} = 100\,W$$

What is the purpose of a Sankey diagram?

To visually show the flow of energy, where the width of each arrow is proportionate to the amount of energy flow.

How is density defined and calculated?

Density is a physical property describing how much mass is contained within a certain volume, calculated as $\text{Density } (kg/m^3) = \frac{\text{mass } (kg)}{\text{volume } (m^3)}$.

What is the density of bamboo if a mass of $38\,kg$ occupies a volume of $0.095\,m^3$?

$$\text{Density} = \frac{38\,kg}{0.095\,m^3} = 400\,kg/m^3$$

Why is a neutron star considered the most dense object in the universe?

Because it contains a few solar masses squeezed into a radius of only $20\,km$, making a thimble full of its matter weigh millions of tonnes on Earth.

What is the difference between a pure substance and a mixture?

A pure substance is made up of only $1$ substance, whereas a mixture is made up of $2$ or more substances that can be physically separated.

What is the difference between an element and a compound?

An element is made up of only $1$ type of atom, whereas a compound is made up of $2$ or more types of atoms chemically bonded.

What is the difference between homogeneous and heterogeneous mixtures?

Homogeneous mixtures (solutions) have components evenly distributed with a uniform composition, while heterogeneous mixtures (suspensions) have components that are not evenly distributed.

In a solution, what are the functions of the solvent and solute?

The solvent is the substance that dissolves other substances, and the solute is the substance being dissolved.

What is the chemical composition of brass?

Brass is made up of approximately $66\%$ copper and $34\%$ zinc.

What is the difference between a saturated solution and a supersaturated solution?

A saturated solution is one where no more solute can dissolve in a given volume of solvent, whereas a supersaturated solution contains more dissolved solute than normal under altered conditions (e.g., higher temperature).

What is electric current and in what direction does it flow?

Electric current is a flow of electrons through wires and components, flowing from $\text{negative} \rightarrow \text{positive}$.

How do series and parallel circuits behave differently if one bulb breaks?

In a series circuit, breaking one bulb stops the entire circuit and all bulbs go out; in a parallel circuit, other branches remain complete so the other bulbs stay lit.

How does current behave in a series circuit compared to a parallel circuit?

In a series circuit, current is the same at all points; in a parallel circuit, the current splits/shares between the branches.

How does voltage behave in a series circuit compared to a parallel circuit?

In a series circuit, total voltage is shared between components; in a parallel circuit, each branch receives the full voltage.

What three subatomic particles make up an atom and what are their electrical charges?

Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.

How is the atomic mass number of an element calculated?

$$\text{Atomic Mass Number} = \text{Number of Protons} + \text{Number of Neutrons}$$

What physical properties distinguish metals from non-metals?

Metals are solids at room temperature, lustrous, good conductors of heat and electricity, malleable, and ductile; non-metals are liquids or gases, dull, poor conductors, and neither malleable nor ductile.

What are the maximum electron capacities for the first three electron shells?

The $1\text{st shell}$ holds a maximum of $2$ electrons, the $2\text{nd shell}$ holds a maximum of $8$ electrons, and the $3\text{rd shell}$ holds a maximum of $8$ electrons.

How do column (group) and row (period) numbers on the Periodic Table relate to atomic structure?

The column (group) number equals the number of valence electrons in the outer shell, and the row (period) number equals the total number of electron shells.

What is valency and what do its positive ($+$) and negative ($$-$code) signs indicate?

Valency is the charge of an atom after losing or gaining electrons; a positive ($+$) sign indicates giving away outer electrons, while a negative ($$-$code) sign indicates gaining outer electrons.

What is the trend in reactivity as you move down Group 1 of the Periodic Table?

Metals generally become more reactive as you move down Group 1.