Chapter 2: Molecules and Solutions Flashcards
What are atoms or elements?
- smallest unit of matter
- parts of molecules
- shown on the periodic table of elements
What are molecules and give an ex
they are made up of two or more atoms bonded together. ex: O2
What are compounds and give an example
a compound consists of two or more DIFFERENT elements that can be separated into simpler substances by chemical reactions. ex: NaCl
What does the bonding of elements rely on?
the capability of each to gain or lose electrons
What is an ion?
an atom that has become electrically charged by losing or gaining one or more electrons
What do atoms want?
The same electronic configuration as noble gases for stability (following the octet rule)
What does the valence electrons refer to?
The electrons on the outermost shell
What do the valence/oxidation number refer to?
the number of electrons lost or gained to achieve a noble gas configuration.
What is a polyatomic ion and give an example.
an ion composed of two or more atoms acting as a single unit in chemistry.
ex: NH4^+1
(found on the back side of the periodic table)
What are chemical bonds?
union of two or more atoms through the transfer or sharing of one or more electrons
What do atoms usually try to do?
they try to fill their valence shell (octet rule)
What are ionic bonds?
- formed between a metal or a non-metal
- 1 or more electrons are transferred from one atom (usually metal) t oanother atom (non- metal)
What are covalent bonds formed between
two non-metals where electrons are shared
What are diatomic molecules?
molecules composed only of two atoms of same chemcial elements.
Describe the three bonds of Diatomic Molecules.
single bond shares one pair of electrons (H2)
double bond shares two pairs of electrons (O2)
triple bond shares three pairs of electrons (N2)
What are ions
In a single atom, chargé results from having either more electrons or less electrons than protons.
More electrons than protons= negative charge
Less electrons than protons= positive charge
Describe the 5 step cross over rule
- Write ions side by side (metals first
- Write the ion charge
- Cross-over to determine number of each element
- The number from the charge of 1st ion gives the number of the 2nd ion and vice versa.
- Simplify and/or drop any “1”
Give an example of cross over
Step 1: Ca^2+ O^2-
Step 2: Ca^2 O^2
Step 3: drop the twos
Step 4: CaO
How does polyatomic ion act when balancing charges in compounds. Give an example
Acts as a single unit with a charge
Ex: NH4^1+. PO4^3-
(NH4)3PO4
What does nomenclature mean
Naming things
What are noble gases
Monatomic
What are all gaseous reacting elements
Diatomic
What are halogens
Diatomic
How do u nomenclature covalent.
-it is only two non-metals
-name each element (start with the positive one)
-end the last element in “ide”
-add prefixes to show more than 1 atom
