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What are chemical bonds?
- The forces that hold together atoms and molecules.
- Electrons are shared in ways that bond the atoms or molecules together.
What is a valence shell?
The outer most electron shell of an atom that has electrons.
What is the octet rule? Duplet rule?
Atoms and molecules try to have a full valence shell of either 8 or 2 electrons (depending on shell cap) by giving, loosing, or sharing electrons with other atoms and molecules.
What determines what type of chemical bonds molecules have?
The way in which they gain or loose electrons; either by giving, loosing, or sharing them.
What is an ionic bond?
- The force of attraction that holds together ions of opposite charges.
- Ionic bonds are stronger than other bonds.
- When an atom/molecule looses or gains an electron to fill each others valence shells, the ratio of protons to electrons of each atom changes, which makes one atom positive, the other negative (ions).
- OPPOSITES ATTRACT, so these two ions now form an ionic bond with positive, and negative sides like a magnet.
- Forms compounds like NaCl (Na ion and Cl ion)
What is a cation?
- A positively charged ion.
- Forms ionic bonds with negatively charged ions.
What in an anion?
- A negatively charged ion.
- Forms ionic bonds with positively charged ions.
What are the characteristics of ionic compounds? (formed by ionic bonds)
- Usually exist as a solid.
- The ions form orderly, repeating structures. (Teeth and Bones, also crystals as in NaCl)
- The amount of ions can vary, but the ratio of cations to anions is always 1:1.
What is an electrolyte?
- A ionic compound that breaks down into positive and negative ions in solution.
- Electrolytes conduct electricity in solutions.
What is a covalent bond?
- Where atoms share electrons instead of loosing or gaining them to fill their valence shells (octet or duplet). Two or more atoms can share one atoms electrons.
- Atoms can share 1, 2, or 3 PAIRS of valence electrons.
- The larger the number of electron pairs shared the stronger the covalent bond.
- Most common chemical bond in the body.
What is a non-polar covalent bond?
- A covalent bond where the electrons are shared equally between the two atoms.
- One atoms nucleus (protons) does not have a greater pull on the electrons.
What is a polar covalent bond?
- A covalent bond where two atoms share electrons unequally.
- One atoms nucleus (protons) has a greater pull on the electrons.
- Its atoms have partial positive, and partial negative charges.
What is electronegativity?
- The power to attract electrons.
- The amount of pull an atom has on electrons (from protons in the nucleus) in a covalent bond.
- A greater electronegativity means that an atom in a polar covalent bond has more pull on the shared electrons which gives it a partial negative charge, which means the other atom has a partial positive charge sense its protons are not balanced by its electrons.
What is a hydrogen bond?
- A hydrogen bond forms from the attraction of partial negative and partial positive charges between molecules with polar covalent bonds.
- These bonds are not strong enough to create molecules, but create links between molecules or parts of a large molecule.
- ***form from parts of oppositely charged molecules attracting***
What is surface tension?
The measure of difficultly in stretching or breaking the surface of a liquid.
What are some properties of hydrogen bonds?
Hydrogen bonds are weak, but large molecules might have thousands of them, which gives them enough force to even influence the 3-dimensional shape of the molecule.
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