Chemical Bonding Part 1 Flashcards
Electronegativity
atoms relative ability to attract/pull on electrons while bonded
Ion
atoms with a charge of either positive or negative charge
Cation
- an atom that has lost electrons
- has a positive charge
- are mostly metals
Anion
- an atom that has gained electrons
- has a negative charge
- are mostly nonmetals
Covalent bond
- Sharing of electrons
- Attraction of nucleus to another atoms electrons
Ionic bond
- transfering/stealing of electrons
- Comes from the word ion
- Attractions of oppositely charged ions
Polar covalent bond
- electrons shared unequally
- unequal distribution of energy
Nonpolar covalent bond
- electrons shared equally
- equal distribution of energy
Formula unit
- the simplest combination of ions that make a neutral compound
- corresponds with a chemical formula
Ionic compound
- a compound made up of positive and negative ions whose charges add to zero
- electrons gained = electrons lost
- they are often binary
Lattice energy
- energy released when 1 mole of an ionic crystalline compound is formed from separate atoms
- Unit: kJ/mol or J/mol
- lattice energy is always (-) b/c that means energy that is released
Polyatomic ion
- molecules with an overall net charge
- atoms are bonded covalently but the atoms have picked up or lost electrons along the way
Oxyanion
- negatively charged polyatomic ions containing oxygen
- (-ate/-ite) -ate will always have 1 more oxygen than -ite
Molecular mass
- the mass of one molecule
- used for covalent bonding
Molar mass
- the mass of one molecule
- used for covalent bonding
Formula mass
- the mass of a single formula unit
- measured in AMU
Percent composition
- The percentage of the compound that is made up of a certain element
- the part element divided by the total compound times 100
Periodic trend for electronegativity and why
- Increases across periods
- Greater nuclear charge and a smaller radius across periods.
Group trend for electronegativity
- Decreases down groups/families
- Larger radius and shielding effect(weaker pull)
what are the two main types of bonding?
covalent and ionic bonding
Explain in depth, ionic bonding
- a transfer of electrons
- one is stealing electrons from another
- between nonmetals and metals
- metal loses electrons as they are weaker and the nonmetals gain electrons as they are the stronger ones.
Explain in depth, covalent bonding
- sharing of electrons
- none gain or lose electrons but one can have more pull than another
- between two nonmetals where they both want to share extra electrons
- if they are equally shared, it is nonpolar but if they are unequally shared, it is polar.
How do you use EN difference to predict type of bond?
- Between two elements, you must find the difference between their electronegativities.
If the difference is greater than 1.7, then it is…
an ionic bond
If the difference is less than 1.7 but greater than 0.3, then it is a…
polar covalent bond
If the difference is greater than 0 but less than 0.3, then it is a…
nonpolar covalent bond
how do ionic bonds form?
- First, one atom steals electrons from another
*Now the atoms are no longer neutral and the oppositely charged ions attract. - Then, the charged ions attract to form an ionic bond.
How do you use electron configuration and octet rule to predict how ionic compounds will form?
- You can figure out how many valence electrons with it
- If the element has 1-3 VE, then they will lose electrons and have a positive charge
- If the element has 5-7 VE, then it will gain electrons and have a negative charge
- If there are 4 VE, the element has to choose to lose/gain 4 valence electrons depending on the other element.
Why we don’t describe ionic compounds in terms of molecules?
- They are formed from their big differences in electronegativities
- Covalent compounds form molecules
What holds ionic bonds together?
- The form from the attraction between ions
- The negative and positive charges attract to each other, holding the ions together
How do you write chemical equations to describe ionic bonding?
- You start off by writing the simplest drawing of the compound, with the charges too
- Then, you make it by adding a plus sign
- After that, you add subscripts with charges
- Finally, you make the equation with just the element’s symbol and subscript, no charge.
How/why ionic compounds form a crystal lattice?
- Ionic compounds form a crystal lattice by holding all the ions together b/c they are oppositely charged
- The shape is then determined by the ratio of ions and the size of ions
How does lattice energy relate to various properties of ionic compounds?
- When the lattice energy –> higher, it causes ionic compounds to change.
*Substance becomes harder
*Has a higher melting point
*Has a higher boiling point.
Names and formulas of common polyatomic ions
Ammonium: NH4+1
Hydronium: N3O+1
Nitrite: NO2-1
Nitrate: NO3-1
Chlorite: ClO2-1
Chlorate: ClO3-1
Perchlorate: ClO4-1
Hypochlorite: ClO-1
Hydroxide: OH-1
Cyanide: CN-1
Carbonate: CO3-2
Hydrogen Carbonate: HCO3-1, Hydrogen Sulfate: HSO4-1
Sulfite: SO3-2
Sulfate: SO4-2
Peroxide: O2-2
Chromate: CrO4-2
Phosphate: PO4-3
Acetate: C2H3O2-1
How to write chemical formulas for ionic compounds
- First, figure out the symbol for the element
- Then, figure out the VE of the elements to find the charge
- After that, if they equal each other out, then you keep them and add nothing
*On the other hand, if they are unequal, you figure out how much of each element is needed to make it equal
*Then for the subscript, you put how much of that element you added
How to name ionic compounds
Rule 1:
* Always put the cation first and anion second
* Put subscripts to show how many of each element there is
* If there is more than one polyatomic ion, use parentheses and a subscript to show how many.
Rule 2:
* If the cation is a transition metal, tin, or lead, you write its charge in a roman numeral in parentheses * To write the name of the anion, if it is a monatomic ion, then change the ending to “ide”
* If the anion is polyatomic, the ending stays the same.
How to convert between moles, grams and formula units for ionic compounds
Mass(g) –> moles: divide by the molar mass
Moles –> mass(g), multiply by molar mass
Moles –> atoms, divide by avogadro’s number
Atoms –> moles, multiply by avogadro’s number
How to calculate percent composition WITHOUT lab data
- Find the element’s atomic masses on the periodic table
- Then, add them together, all of the elements, to find out the total mass of the compound
- After, do the rest normally by putting the element over the compound to find the percent composition.
How to calculate formula mass
Take the atomic masses of each other and the elements in the equation and add them all together. In the end, put AMU as the unit for formula mass.
How to calculate molar mass
Take the mass of each molecule and add it together. So, the mass of one molecule as a whole number.
why can’t you calculate molecular mass for NaCl and what can you of instead?
- You would use formula mass
- These compounds form crystal lattice, not molecules
what happens when lattice energy is released?
- makes bond more stable
- potential energy goes down
atoms bond to become more stable which lowers their what?
potential energy
ionic bonding on main group elements
- s + p blocks
- charges are consistent
*
ionic bonding on transition/inner transition elements
- charges vary
- always cations(lose electrons)
- all have 2 VE
common properties of ionic compounds
- hard to the touch
- brittle
- high melting/boiling point
- dissolve in water
how to break ionic compounds
- lots and lots of energy needed
- dissolving in water too
*good conductors of electricity
what is the formula for percent composition
(part of compound/total compound) x 100
