physical changes Flashcards
(46 cards)
How many electrons can fit on the third shell?
18
The maximum number of electrons in a shell is given by the formula 2n², where n is the shell number.
How is the periodic table arranged?
In order of atomic number
The atomic number represents the number of protons in an atom.
What are groups on the periodic table called?
The columns
Groups contain elements with similar chemical properties.
What are the rows on the periodic table called?
The periods
Each period corresponds to the number of electron shells in the elements.
What does the group number tell you about an atom of an element in that group?
The number of electrons on the outer shell
This affects the chemical behavior of the element.
What does the period tell you about an atom of an element in that group?
The number of shells the atom has
This indicates the energy levels of the electrons.
What is meant by a physical change?
When the particles rearrange but no new chemicals are formed
Physical changes are usually reversible.
Give two examples of physical changes.
- Changes of state (e.g., melting or boiling)
- Separating mixtures (e.g., filtration, distillation)
These processes alter the form of a substance but not its chemical composition.
What is a chemical reaction?
A reaction where a new substance is made
Chemical reactions involve the rearrangement of atoms.
What is a solution?
Formed when a solid dissolves in a liquid
Solutions are homogeneous mixtures.
What is a solute?
The solid that dissolves in a liquid
In a solution, the solute is present in a lesser amount.
What is a solvent?
The liquid a solid dissolves into
Solvents are typically present in greater amounts in a solution.
What word do we use to describe how easily a solute dissolves?
Solubility
Solubility can vary based on temperature and pressure.
What affects the solubility of a solid?
Temperature
Generally, higher temperatures increase solubility.
How does temperature affect the solubility of a solid?
The higher the temperature, the greater the solubility
This is particularly true for most solid solutes in liquid solvents.
What is a saturated solution?
One in which more solute cannot dissolve
A saturated solution has reached its maximum solute capacity at a given temperature.
What is evaporation?
When liquid turns to a gas at the surface of a liquid
Evaporation occurs at any temperature.
Give 3 ways evaporation is different from boiling.
- Happens at any temperature
- Only happens at the surface of the liquid
- No bubbles of gas are seen
Boiling occurs at a specific temperature and throughout the liquid.
What is an atom?
Smallest piece of an element
Atoms are the basic building blocks of matter.
What is an Element?
Substance made of 1 type of atom. Listed on the Periodic Table
Elements are pure substances that cannot be broken down into simpler substances.
What is a Compound?
Substance made of 2 or more elements chemically joined
Compounds have different properties than the elements that form them.
What is meant by pure?
Substance made of 1 type of particle
A pure substance cannot be separated into other materials by physical means.
What is meant by a mixture?
Two or more different particles not chemically joined in a space e.g. salt water, air
Mixtures can be separated by physical means.
What is meant by a Molecule?
Particle made of more than one atom chemically joined. The elements are usually non-metals
Molecules can consist of the same or different types of atoms.