Chemical Bonds Quiz 1 Flashcards
when a new bond is formed, energy is (released/absorbed)
RELEASED - making it an exothermic process
when a bond is broken, energy is (released/absorbed)
ABSORBED- making it an endothermic process
IT TAKES ENERGY TO BREAK A BOND
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when does bonding occur?
when electrons are shared or transferred between atoms (all about valence electrons!!)
the number of valence electrons involved determines the bonding ratio
life hack: CRISS CROSS oxidation states with subscripts
Metallic Bonds
occur between metals
Ionic Bonds
transfer of electrons between metals and non metals
Covalent Bonds (x2)
sharing of electrons between nonmetals (two types: polar covalent and non polar covalent)
_____atoms are surrounded by a sea of mobile electrons. this free electron behavior accounts for conductivity and magnetism.
METAL
why are metallic bonds possible?
because metals have very few valence electrons with low ionization energies.
why are metals malleable?
because the atoms are free to move to new locations while the “sea” of electrons still surround them.
what does an IONIC BOND result from?
the attraction between two oppositely charged ions (metal and nm)
example: sodium and chlorine
what are ionic compounds?
crystal lattices of positive and negative ions
ALL COMPOUNDS WITH POLYATOMIC IONS HAVE BOTH COVALENT AND IONIC BONDING!!
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what are ANIONS?
(ionic bonds) negatively charged- non metals and most polyatomic ions
what are CATIONS?
(ionic bonds) positively charged - metals and few polyatomic ions
why do ions bond to other ions?
SO THAT THE CHARGE IS NEUTRALIZED! also- each ion has a full octet of electrons
characteristics of IONIC SOLIDS?
- very strong force holding oppositely charged ions together
- high melting point, high boiling point
- can dissolve in water and dissociate (ions come apart)
- the solution of ions can then conduct electricity (= electrolytes)
molecular solids?
- formed by covalent bonding (either polar or non polar)
- form individual models which can attract to each other
- easily melted and boiled
- soft solids (wax, butter, ice)
network solids?
- typically formed by non polar covalent bonding
- does NOT form separate molecules
- forms one single crystal made of nonmetal atoms connected by one continuous network of covalent bonds with no areas of weakness that can break apart.
- ex- quartz, diamonds, sapphires
- do not conduct electricity, poor conductors of heat
- hard but brittle
in a single covalent bond ___ electrons are shared between two atoms
2
atoms share _____ electrons to form a double bond
4
atoms share ____ electrons to form a triple bond
6
All ELECTRONS MUST BE PAIRED!!!
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Non Polar Covalent Bonds
electrons are shared equally and are just as likely to be found around either molecule
Polar Covalent Bonds (H2O!!!)
electrons are shared UNEQUALLY and electrons are more likely to be around one atom (the more electronegative atom hogs the electrons!)
POLARITY = ________
separation of positive and negative charge
Non-Polar Bond=
bonding electrons are shared equally
Polar Bond =
electrons are shared UNEQUALLY
how do you determine if a bond is polar?
look at electronegativity difference (table s, subtract)
all polar molecules contain polar covalent bonds but just because a molecule has polar covalent bonds doesnt mean it is a polar molecule.
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EN DIFFERENCE:
1.7 (large) = Ionic
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Polarity in BOND vs. Polarity in MOLECULE
Polar Covalent Bonds: occur when the bond is between two atoms with different electronegativities
Polar Molecules: must have polar covalent bonds and an asymetrical shape
_____ are the forces that hold atoms together in compounds or molecules
chemical bonds
