What are periods in the context of the periodic table?
Rows (vows)
Periods represent the horizontal rows of elements in the periodic table.
What are groups in the context of the periodic table?
Columns
Groups represent the vertical columns of elements in the periodic table.
What do compounds make up?
Most of the matter around you
Compounds are substances formed when two or more elements are chemically bonded together.
Define chemical bond.
Force that holds 2 or more atoms together
Chemical bonds are essential for the formation of compounds.
Which energy level is the lowest energy level?
Electrons closest to the nucleus
The lowest energy level is where electrons are found closest to the nucleus of an atom.
Which energy level is the highest energy level?
Electrons farthest from the nucleus
The highest energy level contains electrons that are farthest from the nucleus.
How many electrons can the lowest energy level hold?
2 electrons
The lowest energy level can hold a maximum of 2 electrons.
How many electrons can the second energy level hold?
8 electrons
The second energy level can accommodate up to 8 electrons.
Define valence electron.
An outermost electron of an atom
Valence electrons are important for chemical bonding and reactions.
What is an Electron Dot Diagram?
A model that represents valence electrons in an atom as dots around the element’s chemical symbol
Electron Dot Diagrams help visualize the number of valence electrons.
In the PES, what do the columns represent?
Valence electrons
The columns indicate the number of valence electrons for elements.
In the PES, what do the rows represent?
Energy levels
The rows indicate the energy levels of the electrons in an atom.
What do unpaired dots in the PES mean?
The number of bonds an atom can form
Unpaired electrons are available for bonding.
What is ionic bonding represented with?
Arrows
Arrows indicate the transfer of electrons in ionic bonds.
How are atoms chemically stable?
When there are 8 valence electrons
This is known as the octet rule.
What are the Noble Gases?
The elements in group 18
Noble gases are known for their chemical stability.
Define a Covalent Bond.
A chemical bond when 2 atoms share one or more pairs of valence electrons
Covalent bonds can be single, double, or triple.
What are the types of Covalent Bonds?
- Single
- Double
- Triple
These types differ based on the number of shared electron pairs.
What is a Covalent Compound characterized by?
Low melting points & boiling points
Covalent compounds typically have weaker intermolecular forces.
What is a Molecule?
The chemically stable unit of a covalent compound
Molecules are formed when atoms are bonded covalently.
Define a Polar Molecule.
A molecule that has a partial negative end and a positive end
Polar molecules result from unequal sharing of electrons.
What is an ion?
An atom that is no longer electrically neutral because it has lost or gained electrons
Ions can be positive or negative depending on whether electrons are lost or gained.
What is a positive ion?
When an atom loses electrons
Positive ions are also known as cations.
What is a negative ion?
When an atom gains electrons
Negative ions are also known as anions.
