Chemistry- Chapter 7-> Sections 7.1-7.2

CHAPTER 7-> Section 1

• Please note the key to better understand the presentation:
• KEY:
• the notes
• important stuff
• other important terms
• my simplified notes

Chemical bonds-

• electrostatic attractions between atoms
• loses energy
• gains stability
• Chemical reactivity- the ease with which an atom can gain or lose an electron

Octet Rule-

• elements are most stable when they have a full valence electron shell
• they want to rearrange the least number of electrons
• < 4 --> lose
• > 4 --> gain
• * less than 4 valence electrons will want to lose them
• & more than 4 electrons will want to gain them

Covalent bonds-

• bonds formed by sharing electrons
• occur between 2 atoms with high electronegativity values
• neither can completely remove electrons for the other
• they share electrons to complete an octet
• most often occur between nonmetals
• -> share electrons
• -> between nonmetals
• -> HIGH electronegativity

Ionic bonds-

• formed by an electron transfer
• occur between 2 atoms with very different electronegativity values
• atom with higher electronegativity takes electrons from the other atom
• this electron transfer forms a cation and an anion, held together through the attraction of opposite charges
• form between metal and nonmetal
• -> ​​​​​​transfers electrons
• -> between metal & nonmetal
• -> forms a cation & anion
• -> DIFF electronegativity- higher takes from lower

Metallic bonds-

• formed by sharing electrons among many atoms
• occur between atoms with low electronegativity values
• these atoms have loosely held valence electrons
• the resulting crystal has mobile electrons that are not associated with any specific nucleus
• most often occur between metals
• -> sharing among many atoms
• -> between metals
• -> low electronegativity

Polarity-

• Polarity- the tendency of an object to form two localized regions of opposite character or charge
• a bond can be described as polar if electrons are unequally shared between two atoms
• NONpolar covalent bond- a bond with equal sharing of valence electrons
• Polar covalent bond- a bond with positive and negative ends caused by the unequal sharing of valence electrons
• -> NONpolar- = (equal)
• -> polar- \= (not equal)

Polarity effects-

• an unequal distribution of electrical charge
• partial charges
• a strong bond- the opposite charges of the atoms hold them together tightly
• bond polarity depends on the difference between the atom's electronegativities
• bonds between diff elements can NEVER be 100% covalent
• bonds (all) can NEVER be 100% ionic

CHAPTER 7-> Section 2

• KEY:
• the notes
• important stuff
• other important terms
• my simplified notes

Covalent Bonding-

• element characteristics-
• similar electronegativities
• nearly full valence electrons shells
• nonmetals
• electron pairs-
• ​​​​​​​bonding pair- two shared electrons
• nonbonding pair- pair of electrons that are not involved in bonding
• double bond- 2 pairs of valence electrons shared
• triple bond- 3 pairs of valence electrons shared
• -> bonding pair- 2 shared electrons
• -> nonbonding pair- 2 electrons not bonded
• -> double bond- 4 electrons shared
• -> triple bond- 6 electrons shared

Number of bonds-

• the number of bonds between atoms in a compound affects the physical and chemical properties of the compound
• bond strength-
• single bonds: weakest
• triple bonds: strongest
• bond length-
• ​​​​​​​single bonds: longest
• triple bonds: shortest
• -> single bonds: weakest, longest
• -> triple bonds: strongest, shortest

Electrostatic Force & Hydrogen 7-

• atoms are held together by an attraction called an electrostatic force
• electrostatic force- the force between electrical charges
• the atoms of hydrogen, nitrogen, oxygen, and the halogens are not stable by themselves
• to exist in a pure form, they must occur as diatomic molecules
• H, N, O, F-I