States of Matter
Name the four states of matter.
Solid, liquid, gas, and plasma.
How does heating a substance affect the motion of molecules in that substance?
Heating increases the molecules' motion.
What is density?
Density is the mass per unit volume.
Name the three particles that make up atoms.
Protons, neutrons, and electrons.
Describe what happens in a chemical reaction.
Reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.
How does heating a liquid affect the speed of the molecules?
Heating a liquid increases the speed of the molecules.
When does evaporation occur?
When molecules in a liquid gain enough energy that they overcome attractions from other molecules and break away to form a gas.
What determines the density of an object?
Density is determine by the mass of the atoms, their size, and how they are arranged.
What is atomic number?
Atomic number is the number of protons in an atom.
How does increasing the amount of reactants affect the amount of products?
Increasing the amount of reactants increases the amount of products.
Why does the alcohol in a thermometer go down when the temperature becomes colder?
When cooled, the molecules in a liquid move slower, causing them to get a little closer together. This results in movement down the thermometer.
What is condensation?
The process in which molecules of a gas slow down, come together, and form a liquid.
Describe the relationship between the density of a sample and the size of the sample.
The density of a substance is the same regardless of the size of the sample.
Give the maximum number of electrons held in:
(1) the first energy level
(2) the second energy level
(3) the third energy level
(1) 2
(2) 8
(3) 8
What is a precipitate?
A precipitate is a solid formed from the reaction of two liquids.
How does the arrangement of molecules in a solid differ from the arrangement of molecules in a liquid?
In a solid, atoms vibrate but stay in fixed positions.
When does freezing occur?
Freezing occurs when the molecules in a liquid slow down enough to arrange themselves into fixed positions as a solid.
What will a solid do in a liquid if the solid is less dense than the liquid?
The solid will float in the liquid.
What happens in a covalent bond?
An atom shares its electrons with another atom, so that both atoms fill their outer shells.
Why does increasing the temperature increase the rate of a chemical reaction?
As more molecules move faster, the number of molecules moving fast enough to react increases, which results in faster formation of products.
Describe the strength of the attractions between molecules in a gas.
In a gas, molecules have very weak attractions for one another.
When does melting occur?
Melting occurs when the molecules of a solid speed up enough that the motion overcomes the attractions so that the molecules can move past each other as a liquid.
What will a liquid do if it is more dense than another liquid?
The more dense liquid will sink.
What happens in an ionic bond?
One atom steals another atom's electrons, leaving one atom with a positive charge and the other with a negative charge. The oppositely charged ions attract.
What is a catalyst?
A catalyst is a substance that can help the reactants in a chemical reaction react with each other faster.