Unit 7 Test Flashcards
(36 cards)
What is an ion?
an atom or group of atoms that have a positive or negative charge
What is an ionic bonds?
ionic bonds form when one atom gives up one or more electrons to another atom. both atoms become charged ions
Why would atoms form ionic bonds?
Atoms want to achieve stability (full shell of electrons). An atom will give one or more electrons to another in hopes of filling both of their octets. This normally happens between a nonmetal and a metal, as metals tend to have less valence electrons and nonmetals have have more, so both of their octets can be filled with one giving or taking electrons from the other.
What is a buffer?
a solution that resists changes in pH
What are the two types of ions?
cations and anions
What are cations?
positively charged ions that are formed by the loss of electrons. metals tend to form cations
What are anions?
negatively charged ions, formed by the gain of electrons
Which atoms tend to give away electrons and which atoms tend to take them?
Metals tend to give away electrons (cations), and nonmetals tend to take electrons (anions)
What types of ions do different elements form?
Metals form cations, and nonmetals form anions
How can we represent an ionic bond? (know how to draw a lewis dot structure of the bond and how it can help us figure out the chemical formula)
- Draw the Lewis Dot diagrams of the atoms
- draw arrow(s) to show the electrons that are being transferred. The arrow will go from the cation to the anion.
- Write the two ions that have formed with element symbol and charge to its top right. the cation goes first. (ex. Na^1+ O^2-)
- criss cross the charge numbers (not the plus/minus signs) to make them subscripts (ex. Na_2 O)
- write the new compound’s complete formula
(i got this from the doodle notes so you can look at those cuz they make more sense)
What are compounds formed by covalent bonds called?
Molecules
Why would atoms form covalent bonds?
Atoms want to fill their shells. This happens normally between nonmetals, as they have more valence electrons, so they can share the number of electrons they are missing.
Which atoms tend to form covalent bonds?
Nonmetals tend to form covalent bonds
How can we represent a covalent bond? (be able to draw a lewis dot structure and know how the structure can help determine the chemical formula)
(this explanation is kinda confusing but the full thing is in the second doodle notes packet)
1. draw the lewis dot diagrams for the atoms
2. rearrange electrons and add additional atoms if necessary
3. circle the new valence shells for each atom. each shell will have 8 electrons
4. write the element symbols and draw in bond lines and lone pairs
5. write the new compound’s molecular formula
If given the electronegativity values of elements from the Pauling Scale, how can you determines if a Polar Covalent or Non-polar Covalent bonds forms?
if the electronegativity differences are less than 0.5, it is nonpolar covalent, if it is between 0.5 and 2, it is polar covalent, and if it is greater than 2, it is ionic
How many bonds do atoms form?
REMEMBER H(hydrogen)-O(oxygen)-N(nitrogen)-C(carbon) 1-2-3-4!
- An atom will form enough bonds to fill its outer shell (octet).
(Ex. Carbon has 4 valence electrons. It will form 4 bonds to get a total of 8 valence electrons.)
- More than one electron pair can be shared at a time forming multiple bonds between atoms.
- Multiple bonds tend to be shorter than single bonds because the atoms are held more tightly together.
Explain what makes a water molecule polar. (What type of bonds are present in a water molecule?)
The electronegativity difference between oxygen and hydrogen is between 0.5 and 2
Be able to draw water molecules and label the elements, identify the partial negative and positive charges and draw in where the hydrogen bonds would form.
i can’t rly explain this on a flashcard but js KNOW HOW TO DO IT hehe :D
What are properties of hydrogen bonds? Can you explain why these properties are a result of hydrogen bonding?
- Intermolecular bond - van der Waals forces
- Formed between molecules that have polar covalent bonds. (large difference in electronegativity)
- H-O, H-N, H-F
- Partial (+) charge of H is attracted to partial (-) charge of a different atom.
know how to place liquids with various pH values
a pH of 0-6.9 is acidic, 7 is neutral, and 7.1 to 14 is a base (alkaline substance)
What is the measure of the hydrogen ion concentration of a solution?
pH
What are solutions with a high H+ (hydrogen ion) concentration called?
Acids
What are solutions with a low H+ (hydrogen ion) concentration, or a solution with a high concentration of hydroxide ions called?
Bases
What are characteristics/properties of ionic bonds?
- Bonds between metals and non-metals
- Electronegativity difference is > 2.0
- High melting/boiling point
- Conduct electricity in solution
