Unit 5 - Chemical Bonds Flashcards
What are chemical bonds? (2)
- The forces that holds atoms together
- VE are shared/transferred between atoms
What is the difference between a compound and a molecule? (2)
- Compounds - Bonds formed between atoms of 2 diff. elements
- Molecules - Bonds can be formed between same element, must be covalent bonded
What are the properties of compounds compared to the properties of the elements from which a compound is formed?
New chemical properties different from the original atoms
What is the energy stored in the bonds?
Potential Energy
Is it an endothermic or exothermic process when a bond forms and breaks?
- Formed Bond - Exothermic, energy is released
- Broken Bond - Endothermic, energy is absorbed
Why do atoms form bonds? (2)
- Atoms want to gain/lose/share e- to achieve 8 VE (stability)
- To reach the lowest energy state possible
Why is the formation of bonds an exothermic process? (3)
- Compounds are more stable than the original atoms
- Atoms move from a higher energy state to a lower energy state
- Excess energy that is no longer needed to be maintained is released
Why is the breaking of bonds an endothermic process? (3)
- Atoms are less stable than the original compound
- Atoms must move from a lower energy state to a higher state
- In order to achieve this, extra energy is needed to be absorbed from the surroundings
What determines the bonding ratios?
Number of VE determines the bonding ratio
What are bonding ratios?
Definition
Proportions of elements that combine to form a compound
Why do bonding ratios occur?
Atoms want to be stable like a noble gas
What is the life hack criss cross method in finding the bonding ratios? (3)
- Identify oxidation states/charge
- Replace OS w/ subscript
- Metals (Cations) are first in bonding sequence
Oxidation States: Li 1+, O 2-
Criss Cross: Li₂O
What are the 4 types of bonds? (4)
- Metallic
- Ionic
- Polar Covalent
- Nonpolar Covalent
What are Metallic Bonds? (5)
- Occurs in a Metal Lattice
- Metals lose e- to achieve the octet rule
- Creates a sea of mobile e-
- Opp. charges of e- hold + ions together (like glue)
- Occurs between metals
Why are metallic bonds possible? (hint: think about the metals themselves!)
Metals have few VE and low ionization energies
What properties are influenced by metallic bonds in metals?
What does free e- behavior accounts for?
- Conductivity
- Magnetism
- Malleability
Definition of Lattice
Regular repeating arrangement of atoms
What are Ionic Bonds (3)
- Electrons are transferred
- Occurs between a metal and a nonmetal
- Strong bond results from the two oppositely charged ions’ attraction
What are a few rules to note for ionic bonds in a lewis dot diagram? (3)
- Brackets are NEVER drawn around the cation
- > 1 cation - Number of cations shown as superscript
- > 1 anion - Number of anions shown as coefficient
What do Ionic Bonds form? (3)
- Ionic Compound
- Crystal lattices of oppositly charged ions
- Charge is neutralized
What are polyatomic ions? (3)
- Two or more atoms bonded together
- Carries an overall charge (forms a single ion)
- Both Ionic and Covalent Bonding
(polyatom itself is covalently bonded, but the ION is ionically bonded with the other polyatomic ion)
Why are metals malleable? (4)
- When a force is applied to a metal
- Metal atoms can slide past each other w/o the structure breaking
- Free e- still surround them & keeps the atoms bonded
- Maintaining the structure of the metallic lattice