Unit Four Flashcards
Polyatomic ion
An ion made up of two or more atoms
PO4-3
Cation
A positive ion Forms from the loss of electrons Metals Mg2+ Li+
Anion
A negative ion Forms from the gain of electrons Nonmetals N3- S2-
Naming cations
Keep the name of their parent ion, add ion to the end
Name an ion of Mg
Magnesium ion
Naming anions
Keep the root of their name but change the ending to ide
Name a nitrogen ion
Nitride ion
Chemical bond
An attractive force between atoms or ions that binds them together as a unit
Why do bonds form?
Decrease potential energy
Increase stability
Compound
A pure substance made of two or more elements that are chemically combined
Monotmic ion
An ion made up of one atom
Na+
Molecule
A special term used to describe compounds that are made by the sharing of electrons (covalent bond)
Binary compound
A compound containing two different elements
CaF2
Ionic bonds
A bond formed from the transfer of electrons (one atom loses electrons and the other one gains them)
Often referred to as salts
What types of atoms can form ionic bonds?
Metal and a nonmetal
Metal and a polyatomic ion
Polyatomic ion and a nonmetal
Two polyatomic ions
Structure of an ionic bond
Crystal lattice
Result of positive and negative ions stacking themselves up so they will be near an ion of opposite charge
Strength of ionic bonds
Very strong because the opposite charges inside attract each other, making it hard to pull them apart
Melting and boiling point of ionic bond
High melting and boiling point because their bonds are very strong so they require a lot of energy to break
Conductivity of ionic bonds
Can conduct electricity when they are dissolved in water or molten, don’t conduct electricity when solid because the ions are locked in place and can’t allow the electrons to flow
Are ionic compounds soft?
No they are hard but very brittle—energy required to break is large, it will shatter whole structure instead of breaking just one
Covalent bond
Forms when two atoms share electrons so they can both satisfy the octet rule. Because they are sharing electrons, there is no cation or anion in a covalent molecule (no charges).
What types of atoms can form covalent bonds?
Formed between nonmetals only
Structure of covalent bonds
Structure can vary
Strength of covalent bonds
Weak—there are positive and negative ions being attracted to each other
Melting and boiling point of covalent bonds
Low melting and boiling point—weak type of bond so less energy to break them
Conductivity of covalent bonds
Don’t conduct electricity—don’t break into ions so electrons can’t flow through
Acids
First element is Hydrogen (H) can be bonded to a nonmetal or polyatomic ion
Technically an ionic bond where H gives away its one valence electron
Only exception is water
Polar covalent bond
Atoms are not equally sharing electrons (this is because one of the atoms is stronger)
Nonpolar covalent bond
Atoms are equally sharing electrons
Get partial charges
Polarity is determined by…
The electronegativity of the atoms bonded together
Electronegativty
The ability for an atom to pull shared electrons towards itself (strength)0
Difference of electronegativities is:
0.5?
_>0.5
_>1.7?
Nonpolar
Polar
Ionic
Bond length from lowest to highest
Ionic
Bond strength from lowest to highest
Nonpolar covalent
Ternary compound
A compound containing three or more different elements
Two rules for writing formulas
Cation has to come before the anion (positive comes before negative)
The charges of the ions have to cancel out, use criss cross rule