Unit 5 Flashcards
What is chemical bonding?
Chemical bonding occurs because of the attraction between positive nuclei and negative electrons. Also known as the glue that holds everything together in matter.
Why is chemical bonding important?
It occurs to make atoms more stable. Atoms without full valence shells are not stable. They become stable through bonding with other atoms.
What is the Octet Rule?
A full valence shell must have 8 electrons. 2 from the filled S orbital (max 2 electrons) and 6 from the filled P orbital (max 6 electrons); 2+6=8
How is the Octet Rule completed?
Atoms will gain, lose, or share valence electrons to become isoelectronic with a noble gas.
Exceptions to the Octet Rule.
Hydrogen and Helium follow the Duet Rule so a full shell has 2 electrons.
Lithium, Beryllium, and Boron can and OFTEN have less than 8 e-.
Atomic numbers greater than 10 can and SOMETIMES have more than 8e-.
What are Electron Dot Diagrams?
A representation of the number of valence electrons in an atom.
Steps for drawing electron dot diagrams.
1: Let the element symbol represent the nucleus and all electrons except the valence electrons.
2: Determine the number of valence electrons; that is the number of dots you must show. (remember these are the A’s)
3: There are 4 “sides” to an element symbol (top, bottom, left, and right). Place 1 dot on one side, then move to the next side. Continue until the 5 dot when you must pair them up.
See diagram on page 2 of note packet.
What is ionic bonding?
The transfer of electrons between atoms due to a large electronegativity difference. The difference is typically 1.7 or larger.
Ionic bonds occur between metals and nonmetals or more generically cations and anions. See pictures on page 5.
What are the properties of ionic bonding?
Ionic bonds are very strong.
Compounds are solid, hard, brittle, and have high melting points.
Forms a crystal structure, which is a regular pattern of repeating ions.
See pictures on page 5.
What are the steps for drawing electron dot diagrams?
1: Draw the electron to diagram for each atom.
2: Show the transfer of electrons with arrows from a dot on the metal to a space on the nonmetal. (You may need to draw multiple arrows to ensure all elements end up with full valence shells).
3: Draw the resulting ions in brackets with charges.
4: Write the formula of the New Ionic compound formed.
You can check if your charges are correct with the periodic table.
