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
What are the prefixes
Mono: 1
Di: 2
Tri: 3
Tetra: 4
Penta: 5
Hexa: 6
Hepta: 7
Octa: 8
Nona: 9
Deca: 10
What is nomenclature ionic
-metal and nonmetal
-name each element
-positive ion first then negative ion
-add “ide” to the second ion
-no prefixes
What is nomenclature polyatomic ions
-metal (positive) first
-then polyatomic (mostly negative) with its normal name
Give an example of a covalent nomenclature name
Pentoxide
Give an example of ionic nomenclature names
Calcium chloride
Give an example of polyatomic ions nomenclature names
Aluminium hydroxide
What is a solution
a homogeneous mixture (parts that can<t be distinguished)
What is a solute
the component of the solution that is dissolved (usually in lesser quantity)
What is a solvent
the component of the solution during the dissolving (usually in greater quantity)
What is an aqueous solution
a solution in which the solvent is water. HCl (Aq)
What is solubility
the maximum amount of solute that can be dissolved in a certain volume of solvent.
what is concentration
the amount of solute in a given amount of solution
What is the formula for concentration
c=m/v
what is the formular for dilution
c1 x v1 = c2 x v2
What is morality /molar concentration
The number of moles of solute in a given amount of solution
What is the formulae for morality
M= n/v
What is the formula for molar dilution
M1 x V1 = M2 x V2
Give an example of ppm
3.2g/L x 3200mg/1L=3200ppm
What is an electrolyte
A substance that allows an electric current to flow through the solution
What is electrolytic dissociation
The separation of a dissolved compound into 2 ions of opposite charges
Give an example of electrolytic dissociation equation
Na+1 (aq) + Cl-1 (aq)
What is the electrolytic conductivity of a solution
It’s a measure of its ability to allow an electric current to flow through it during to the ions carrying the change
what does the strength of an electrolyte depend on
on its degree of dissociation:
- some dissociate 100% into ions so they carry electricity easily
- some dissociate into few ions so they carry electricity weakly
- some do not dissociate at all so they do not carry electricity at all.
what is an acid
a substance that gives h+ ions in water
chemical formular for acid usually starts with
usually starts with H
what is the pH of an acid
[0,7[ litmus paper turns red
what is the exception of acids
CH3COOH
what is a base
substance that gives OH-1 ions in water
what does the base formula usually end with
OH (generally combinatin of a metal and OH)
what is the pH of a base
]7.14] litmus paper turns blue
what is the exception for a base
ammonia
what is a salt
a substance produced from the bonding of a
metallic ion and a nonmetallic ion.
explain the formula of a salt
They don’t start with H or end with OH (Always a
combination of Metal and Non-Metal)
explain the pH scale of a salt
They can be acidic, basic or neutral
explain what neutralization is
acids and bases neutralize each other and the product is always neutral.
give the formula for neturalization
Acid + Base = Salt + Water
what is an indicator used for
used to detect the presence of an acid or a base. some reveal the exact pH
