Chapter 1

What is an ion?

An atom that has gained or lost electrons, giving it an electrical charge.

What is a cation?

A positively charged ion formed when an atom loses electrons. (Memory trick: The "t" looks like a plus sign +).

What is an anion?

A negatively charged ion formed when an atom gains electrons. (Memory trick: A Negative Ion = Anion).

If an atom loses all of its electrons, does it change into a new element?

No. An element's identity is determined by its protons, which never change during ionization.

Why can lightning travel through ionized air but not normal air?

Ionized air has free, moving electrons stripped by a powerful electric field, allowing it to conduct electricity like a wire.

What is the difference between changing an atom's electrons vs. changing its neutrons?

Changing electrons changes the charge (making it an ion); changing neutrons changes the weight (making it an isotope).

What kind of electrical charge does an electron have?

A negative charge. It is the exact opposite of a proton's positive charge.

How much do electrons weigh compared to the nucleus?

Practically nothing. Almost all of an atom's weight is found in its center (the nucleus).

What is an electron shell?

An imaginary sphere or zone around the nucleus where an electron is likely to be found.

What happens to an electron's energy when it jumps to a higher shell further from the nucleus?

Its energy increases. (It loses energy when it falls back down to a lower shell).

Why does electricity almost always come from electrons moving rather than protons?

Electrons sit on the outside of the atom and are lightweight, making them much easier to knock loose and move.

What is the difference between a mixture of gases and a compound?

In a mixture, the gases just float together and keep their traits. In a compound, they chemically lock together to create a brand-new substance.

What happens if you mix hydrogen and oxygen gas and then add a spark?

A violent explosion occurs, and the atoms instantly merge to form the compound water.

Do compounds look and act like the elements that make them up?

No. Their properties drastically change. For example, two invisible gases (hydrogen and oxygen) combine to make liquid water.

Do all chemical compounds form at the same speed?

No. Some happen instantly with an explosion (like water), while others happen very slowly over time (like rust).

What is a molecule?

A cluster of two or more atoms stuck together like LEGO bricks (can be the same element or different elements).

What do monatomic, diatomic, and triatomic mean?

Monatomic = 1 lone atom (O) | Diatomic = 2 atoms grouped (O₂) | Triatomic = 3 atoms grouped (O₃, ozone)

What is the difference between a molecule and a compound using the analogies?

Stacking bricks = Molecule (any group of atoms) | Marrying different elements = Compound (different types of atoms transformed together).

How do molecules move inside a solid?

They are locked in a rigid grid and cannot move around, so they just vibrate in place.

How do molecules move inside a gas?

They have lots of space and fly freely at high speeds, occasionally crashing into each other.

What is an electrical conductor?

Any material that lets electrons flow through it easily (like a smooth highway for electricity).

What is the best conductor at room temperature, and what do we actually use in wires?

Silver is the best, but copper and aluminum are used in wires because they are much cheaper.

Do salt water and normal air conduct electricity well?

Salt water = Yes (salt helps it conduct) | Normal air = No (unless it becomes ionized).

How do electrons physically travel through a wire, and in what direction?

They "jump" from atom to atom, traveling away from negative areas toward positive areas.

What is an electrical insulator?

A material that blocks electrons from moving, stopping electrical traffic like a brick wall.

What are some common examples of good insulators?

Plastics, glass, dry wood, dry paper, normal air, and pure water.

Why is an insulator sometimes called a dielectric?

Because it can keep positive and negative charges separated on opposite sides without letting them flow together.

Can an insulator ever be forced to conduct electricity?

Yes. Extreme voltage or heat can force ionization, charring, or melting, which breaks the material down and lets electrons through.

What is a resistor?

A component made to slow down and control electron flow (like an electrical speed bump).

What is the relationship between conductivity and resistance?

They are exact opposites. As conductivity goes up, resistance goes down (and vice versa).

What unit do engineers use to measure electrical resistance?

Ohms. The higher the ohm value, the more opposition it offers to electrons.

What happens to electrical energy when it fights its way through resistance?

It converts into heat, which causes energy loss in wires but makes appliances like toasters work.

What is the difference between an electron and an ion?

An electron is a single negative particle orbiting the nucleus | An ion is a whole atom that becomes electrically charged by gaining or losing electrons.

How do you explain molecules vs. compounds?

Molecules = atoms stacked like LEGOs (same or different elements) | Compounds = different elements that chemically marry to form a new substance.

What do conductors and insulators do to electron traffic?

Conductors are a smooth highway that lets electrons zoom through easily | Insulators are a brick wall that blocks electron movement completely.

What is the difference between resistors and semiconductors?

Resistors are designed to permanently slow down and control electron flow, whereas semiconductors can change their behavior to act as either a conductor or an insulator depending on the applied signal.

What device converts visible light energy directly into electricity?

A photovoltaic cell (also commonly called a solar cell).

What are infrared (IR) rays?

A form of radiant heat given off by light bulbs and heaters that has a longer wavelength than visible light and cannot be seen.

What is the difference between an electric motor and a generator?

A generator turns physical motion (mechanical energy) into electricity | A motor turns electricity into physical motion.

How do wireless signals travel long distances through space?

Through electromagnetism—changing electric fields and magnetic fields continuously creating each other over and over through space.

Why can a car battery be recharged while a standard flashlight cell cannot?

Forcing an external current backward through a car battery resets the chemical reaction, whereas a flashlight cell's reaction cannot be reversed.