Ch2: Chemical Bonding & Lewis Structures Flashcards
What are anions
Ions carrying a negative charge
What are the three types of chemical bonds?
Ionic bonds, covalent bonds, and metallic bonds
What are cations?
Ions carrying a positive charge
What are ionic bonds?
oppositely charged ions (positive and negative) are held together by electrostatic forces/attractions between them
- electrons are lost or gained
What are covalent bonds?
held together by the mutual attraction to the nuclei of the atoms through the sharing of electrons
- electrons are shared
- non-metals
What are metallic bonds?
electrons are shared between many atoms all at one time and “flow” between atoms
What is electronegativity?
atoms in a bond/molecule/molecular ion and their tendency to attract electrons towards itself
eg) Fluorine is the most electronegative element (top right) and the element’s electronegativity decreases as you move away from fluorine
- electronegativity values can be used to predict the nature of bonds that form between elements
What are ionic compounds?
also known as SALTS
- contains ions held together by electrostatic forces/attractions
- formed by redox reactions between metals and non-metals (large differences in electronegativities)
ALL ABOUT BALANCING THEIR CHARGES - NET NEUTRAL
How do you identify ionic bonds?
- contains any element from group 1 and 2 and any element from groups 17 and 18
- elements in groups 1 and 2 always lose electrons, carry the positive charge, and never participate in covalent bonds
What are nonpolar covalent bonds?
atoms in the bonds have the exact same electronegativity (found in homonuclear diatomic species)
- electrons are shared equally between the atoms
What are polar covalent bonds?
- electrons are shared UNEQUALLY
- polarized towards the atom with greater electronegativity
- atoms have PARTIAL CHARGES (+ and -)
- elements with the greatest electronegativity differences will have the most polar bonds
- one atom has more electron density than the other
What is a redox reaction?
A reaction in which the metal loses electron(s) and the nonmetal gains electron(s)
LEO says GER
lose electrons - oxidization
gain electrons - reduction
What are the three characteristics to describing a bond?
- bond order
- bond length
- bond dissociation energy
What is bond order?
number of bonds - single, double, or triple bond
What is bond length?
distance between the two nuclei participating in the bond
What is bond dissociation energy? (bond strength?)
amount of energy required to completely separate the two bonded atoms
Describe the relationship between bond length, bond order, and bond dissociation energy.
As bond order increases, bond length decreases, and bond dissociation energy also increases!
What is percent ionic character?
A ratio that helps us determine if the bond is covalent or ionic
Although covalent and ionic bonds exist, no bond is _____________________________________
Although covalent and ionic bonds exist, no bond is TRULY ONE OR THE OTHER!!
What are the two concepts associated with Lewis Structures?
the octet rule and formal charge
What is the octet rule?
an atom that satisfies the octet rule has EIGHT VALENCE ELECTRONS
How do you determine if an atom satisfies the octet rule?
- Count the lone pair electrons
- Count all bonding pair electrons (twice the # of bonds)
- Add numbers of from 1 and 2, if it adds to 8, then you have a full octet!
- if not then you have an incomplete octet or hypervalent (expanded octet)
What are the 4 exceptions to the octet rule?
- Hydrogen - can only have max 2 electrons/only one bond
- Electron deficient species - incomplete octet, elements in group 13 can have just six valence electrons in their valence shell
- Hypervalent - expanded octet, opposite of electron deficient, containing elements in the p-block third row and below that may have more than an octet of electrons
- Free radicals - species containing unpaired electrons (very reactive), an odd # of electrons indicate that you’re dealing with a radical
What is formal charge?
the difference between the # of valence electrons in a neutral atom compared to the # of electrons (lone pairs and bonded pairs) of an atom in a molecule
- formal charges assume that electrons are shared EQUALLY between the bonded atoms