Atoms
What is the smallest building block of matter?
Atoms
What term describes a substance made of only one kind of atom?
Element
What is the name of the change from solid to liquid?
Melting
If an object floats on water, is it more dense or less dense than water?
Less dense than water.
What is a thermal conductor?
A material that allows heat to pass through it easily.
Name the three particles found in matter:
Protons, Neutrons, Electrons
What is a molecule?
Two or more atoms chemically bonded together.
What is the name of the change from liquid to gas?
Evaporation (or vaporization).
What is density?
How much mass (matter) is packed into a given space.
What is a thermal insulator?
A material that slows down or prevents heat from passing through it.
Where (generally) are protons and neutrons located in an atom, and where are electrons found?
Protons and neutrons are in the nucleus (center); electrons orbit or exist in electron clouds around the nucleus.
How is an atom different from a molecule? Give one clear difference.
An atom is a single particle of an element; a molecule is two or more atoms bonded together (can be same or different elements).
What is the name of the change from gas to liquid?
Condensation
If a block and a ball have the same mass but the block takes up more space (larger volume), which one has lower density and which will float?A
The one with larger volume has lower density and is more likely to float.
Give two examples of good thermal conductors and two examples of good thermal insulators?
Conductors: metal spoon, aluminum foil. Insulators: foam, wood, cloth, rubber gloves.
What is the electrical charge of a proton, a neutron, and an electron?
Proton: positive +
Neutron: neutral 0
Electron: negative -
Give an example of a molecule made of two different elements and name the elements.
Water (H₂O) — hydrogen and oxygen
Carbon Dioxide (CO2)
Describe the particle arrangement (how particles are arranged and move) for a solid, liquid, and gas in one or two short sentences each
Solid: particles are tightly packed and vibrate in place; Liquid: particles are close but can slide past each other; Gas: particles are far apart and move freely.
Explain why oil floats on top of water.
Oil is less dense than water, so oil sits on top of water.
Why does a metal pot feel hotter than a wooden spoon when both are in hot soup?
Metal is a good conductor and transfers heat quickly to your hand; wood is an insulator and conducts heat slowly.
If an atom has 6 protons and 7 neutrons, how many electrons does it have?
6
Explain why O₂ and H₂O are both molecules but only H₂O is a compound (define compound).
O₂ is a molecule made of two oxygen atoms of the same element; H₂O is a molecule made of two different elements (hydrogen + oxygen), so H₂O is a compound (a molecule made from atoms of different elements).
Identify and define two less-common phase changes:
Sublimation: solid changes directly to gas without becoming a liquid; Deposition: gas changes directly to solid without becoming a liquid.
A piece of metal sinks in water but floats on mercury. Explain using density.
The metal is denser than water (so it sinks) but less dense than mercury (so it floats on mercury).
A lunchbox company must choose a material to keep food warm. Would you suggest using a metal container or a container lined with foam? Explain your choice in 2–3 sentences and use the terms conductor or insulator.
Foam-lined container — foam is an insulator and will keep heat from escaping, so food stays warmer longer; metal alone would conduct heat away faster.