Chem - 7/8 (bonding) Flashcards
what s bonding
how and why atoms come together to make compounds
how many types of bonding are there
2
what are the two types of bonding
ionic and covalent
what happens to the electrons in ionic bonding
electrons are transferred
what are valence electrons
the electrons on the very outside of an atom
why do the noble gases typically not react
they have a full outer shell of valence electrons
how many valence electrons do most elements want
8
how many valence electrons does hydrogen want
2
how many valence electrons does Helium have
2
would lithium and fluorine form an ionic compound
yes
would potassium and helium form an ionic compound
no
is CO2 ionic
no
is CaS ionic
yes
what are 3 properties of ionic compounds
most are crystalline solids at room temperature
generally have high melting points
can conduct an electric current when melted or dissolved in water
why are ionic compounds typically solids at room temperature with high melting points
bc of the orderly arrangement of their ions
each ion is attracted to the ion it is next to so there is less repulsions which results in a stable structure
why are ionic solids able to conduct electricity when melted or dissolved in water
the ions are free flowing
how can you model the valence electrons of metal atoms
as a sea of electrons
what is an alloy
a mixture composed of two or more elements, at least one of which is a metal
why are alloys important
their properties are often superior those of their component elements
is the formation of an alloy a chemical or physical change
physical because its a mixture and you can separate it into its components
what information does a molecular formula provide
how many atoms of each element a substance contains
what is a molecule
a neutral group of atoms joined together by covalent bonds
what is a molecular compound
a compound that is composed of molecules
what is the difference between ionic and covalent bonds
ionic bonding involves the transfer of electrons while covalent bonding involves the sharing of electron
Does a molecular formula tell you anything about the structure of a molecule
No
Does a molecular formula tell you anything about the structure of a molecule
No
What representative units define molecular and ionic compounds
MC is molecule
IC is a formula unit
Compare and contrast melting and boiling points of molecular and ionic compounds
MC have lower melting and boiling points
Compare and contrast the states of matter of molecular and ionic compounds
Many MC are gases or liquids at room temperature, while many IC are crystalline solids
What is a single covalent bond
A bond formed when two atoms share a pair of electrons
What is an unshared pair
A pair of valence electrons that is not shared between atoms
What is a double covalent bond
a bond that involves two shared pairs of electrons
What is a triple covalent bond
a bond formed by sharing three pairs of electrons
What is a resonance structure
One of the two of more equally valid electron dot structures that have the same number of electron pairs for a molecule or ion
What is the VSEPR theory
Electrons want to stay far away from each other, so the shape of the molecule will adjust to honor this
What does VSEPR stand for
Valence shell electron pair repulsion
What is the degree of the tetrahedral angle
109.5
Do unshared pairs affect the structure of molecules
Yes
What is electronegativity
How much a bonded atom likes electrons
What us the most e neg element
Fluorine
What is the least e neg element
Francium
What does hydrogen have the same e neg as
Carbon
For which kind of bonds is polarity important
Covalent bonds
When do you have non polar bonds
Anytime two of the same element are bonded together or when Carbon and hydrogen are bonded
When do you have a polar bonds
All other bonds that aren’t between two of the same element or carbon and hydrogen
How are the electrons shared in non polar bonds
Evenly
How are electrons shared in polar bonds
Unevenly
What do you need to know in order to find the polarity of molecules
Dot structure
Bond polarity
Shape
What do we know about a molecule if it only has nonpolar bonds
The whole molecule is nonpolar
What is the difference between intra and inter
Intra - inside/within
Inter - between
Are bonds intramolecular or intermolecular
Intramolecular
What are the 3 types of intermolecular forces
Dispersion, dipole-dipole, and hydrogen bond
List the intermolecular forces in order of weakest to strongest
Dispersion, dipole-dipole, hydrogen bond
Is dispersion force for polar or non polar molecules
Non polar
Is dipole-dipole force for polar or nonpolar molecules
Polar
Is hydrogen bond force important for polar or non polar molecules
Extreme polar
When/why do dispersion forces take place
Even in nonpolar molecules, the electrons randomly move around, which can randomly make one side of the molecule more negative than the other, making it temporarily polar. The shift of electrons in one molecule induces the same shift in the molecules around it
Why are dispersion forces so weak
Because they are temporary
What happens in dipole-dipole forces
A polar molecule induces the same thing in the molecule next to it
Why are dipole dipole forces stronger than dispersion
Because they are permanent
What do we need to form a hydrogen bond
Hydrogen bonded in a molecules to N O or F
Why are hydrogen bonds so strong
Because it’s an attraction between the very positive part of one molecule and the very negative part of one molecule
Why are hydrogen bonds possible
Because whenever hydrogen bonds with N O or F, it already has less electrons (and no lone pairs; it’s a ‘naked proton’) and then N O and F are all more electronegative than H so it makes N, O, or F super negative and leaves H super positive
when elements are shared unequally, chemists characterize these types of bonds as
polar covalent
metals typically have (high or low) electronegativity values
low
what kind of bonds does B2 have
nonpolar
where are the alkali metals
the first column
if atom X forms a diatomic molecule with itself, what kind of bond is it
Nonpolar covalent
where are the alkali earth metals
the second column
where are the transition metals
the middle metals
where are the metalloids
around the staircase
where are the halogens
second to last column
where are the noble gases
last column
The bonds between the hydrogen and oxygen atoms in a single water molecule are called what?
Polar covalent bonds
Why is aluminum better than boron, oxygen, or hydrogen to make wire from
It is a metal, so it conducts electricity better because it has free flowing electrons
The dot structures of charged molecules have to be in what
Brackets with the charge written on the outside!!!
