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 the oxidation states - Li +1, O 2-
- Take oxidation state and replace it with the subscript
(Li^1 and O^2 criss cross to become Li₂O, because the 1 from Li becomes subscript for O, and the 2 from O becomes the subscript for Li) - Metals will always be a cations, and cations tend to be first in the bonding sequence
Essentially, it is finding the number of atoms itwill take to cancel out the oxidation states or charges of the atoms to make the bondage neutral.
What are the 4 types of bonds? (4)
- Metallic
- Ionic
- Polar Covalent
- Nonpolar Covalent
What are Metallic Bonds? (4)
- Metals want to lose electrons to achieve the octet rule (metal atoms are in a lattice)
- Creating a sea of mobile electron
- The opposite charges of electrons help hold the positive ions together, acting as a 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