Chapter 10 Flashcards
Why do bonds form?
Chemical bonds form because they lower the potential energy between charged particles that compose atoms
What are the three types of bonds?
Ionic, Covalent and metallic
What types of atoms are involved in a ionic bond?
metals and nonmetals
What types of atoms are involved in a covalent bond?
nonmetal and nonmetal
What types of atoms are involved in a metallic bond?
metal and metal
What happens to the electrons in each type of bond?
Ionic electrons are transferred, covalent electrons shared, and metallic electrons pooled
Do metals have low or high ionization energies?
low, electrons are relatively easy to remove
nonmetals have what type of electron affinity?
negative, ready to gain electrons
What is the simplest model for metallic bonding?
Electron sea model
What is a lewis symbol?
Symbol of an element durrounded by dots representing the elements valence electrons
number of valence electrons for a main group element is equal to what?
group number of element, except for helium
Does the location of the dots matter in lewis symbol?
No, but place dots singly before pairing
What does an octet sygnify in alewis diagram?
octet is eight dots around element, signify filled outer eletron shell for s and p block elements. Very stable, s and p sublevels are filled
octet rule
tendency for most bonded atoms to posses or share eight electrons in their outer shell to obtain stable electron configurations and lower their potential energy
How to write lewsi symbol of anion
charge in upper right hand corner outside of brackets
What is lattice energy?
energy associated with forming crystalline lattice from gaseous ions
What interactions must be considered to caluclate potential energy?
nucleus to nucleus repulsions, electron to electron repulsions, nucleus to electron repulsions
Most bonds have some degree of what?
sharing (covalent) and ion formation
How are bonds classified as covalent if there’s some ionic transfer of electrons?
Bonds are classified as covalent if the amoutn of electron transfer is insufficient for the material to display the classic properties of ionic compounds
How are bonds clasified if unequal sharing creates a dipole in the bond?
bond is classfied as polr covalent
How are bonds classified as polar covalent?
If the sharing is unequal enough to produce a dipole in the bond
What happens to the atoms in polar covalent bond?
One atom pull electrons closter to its side
One end of the bond has larger electron density than the other
Describe bond polarity (polar covalent)
The end with larger electron density gets a partial negative charge. The end that is electron deficient gets a partial positive charge
What is electronegativity?
Ability of an electron at attract bonding electrons to itself
The larger the difference in electronegativity,
The more polar the bond
What are the electronegativity trands on the periodic table?
- flourine is the most electronegative
- Francium is the least electronegative
- noble gases are not assigned EN values
- increases from left to right
- increases as you go up to flourine
How many valence electrons does the column with hydrogen have?
1
How many valence electrons does the column with beryllium (Be) have?
2 valence electrons
How many valence electrons does the column with boron (B) have?
3
How many valence electrons does the column with carbon have?
4
How many valence electrons does the column with nitrogen have?
5
How many valence electrons does the column with oxygen have?
6
How many valence electrons does the column with flourine have?
7
How many valence electrons does the column with helium have?
8
What is the formula for formal charge?
fc = number of valence electrons-number of nonbinding electrons-1/2*number of binding electrons
What does the formal charge represent?
Charge an atom would have if all bonding electrons are equally shared
What are resonance strucutres?
Two or more Lewis structures with atoms in same place but with different electron arrangements
What does it mean when the sum of the formal charges is zero?
neutral molecule
What does the sum of formal charges mean for an ion?
equals the charge of the ion
what is the best formal charge for individual atoms?
0
negative formal charge for
most electronegative element
positive formal charge
on least electronegative
What is the incomplete octet exception?
-less of an octet around atom, not enough valence electrons to form an octet around centeral atom
What are free radicals?
- exception to octet rule
- Result of lewis structure with odd number of electrons
- only put 1 electron in lewis struture if there’s an odd nubmer of valence electrons
what is an expanded octet?
- octet rule exception
- greater than octet around atom
- common
which elements on the periodic table can have an expanded octet?
elements on the third row and lower, usually up to 12 to 14 electrons
what type of compouds can have more than one centeral atom in lewis structure?
organic compounds
