unit 4 - ionic, covalent bonding, & metals test

ionic compounds

*electrons transfered

+ & - ions formed by gaining/ losing electrons, cation + anion (positive & negative ion), nonmetal + metal (metal attaches to nonmetal)

characteristics:

• crystalline solids

• high melting/ boiling points

• brittle

• good conductors

• all salts

cation

positive ion, written first!

think: cute cat = +

ex:

• the H⁺¹ in HCN

• cation charge is Co⁺³ in CoCl₃

anion

negative ion, written last

think: onion = -

monatomic anions

ending is -ide in a ionic compound

polyatomic anions

most common endings are -ate & -ite in a ionic compound

building ionic compounds

octet rule: all elements want 8VE (noble gases) to have the electron configuration of a noble gas

ex:

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crisscross shortcut & practice

*charge DOESNT follow

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rules for ionic compounds

• positive & negative ion

• cation + anion

• metal + nonmetal

• crisscross charges

• cation 1st (name stays same)

• anion 2nd (ending changes to -ide)

• s & p elements

• transition elements (charges w/ roman # from list)

• polyatomic (name stays same)

monoatomic ionic practice

ex:

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polyatomic ions

covalently bonded group with an overall charge

ex:

• strontium phosphate-

• colbalt (II) sulfite-

• calcium hydroxide-

• iron (III) bicarbonate-

• NO2-1

• PO3-3

more practice from packet

ex:

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covalent/ molecular compounds

*electrons shared

right side of PT, 2 or more nonmetals

characteristics:

• low melting/ boiling points (gases & liquids)

• poor conductors (no metals)

• gases or liquids, not solids

• use valence e- to build molecules

ex:

• 
  

covalent bonding

# of e- needed = # of bonds, the atom that needs the most e- goes in middle, unpaired e- are shared/ bonded

exceptions to ocetet rule for covalent bonds: covalent bonds make us of shared e- so some molecules form to where they dont follow the rule

ex:

• 
  

lewis dot structure

using valene e-

ex:

• 
  

vsepr theory (valence shell e- pair repulsion)

electron repulsion causes electron pairs to move as far apart as possible affecting the shape of the molecule

shapes:

• tetrahedal - 109.5° = no unshared pairs on central atom

ex:

• pyramidal - 107° = one unsharded pair on central atom

ex:

• bent - 105° = 2 unshared pairs on central atom

ex:

• linear - 180° = 3 atoms, no unshared pairs or 2 atoms

ex:

single covalent bond

one pair of electrons shared between 2 atoms, single bonds have LOWEST dissociation energy (ability to break bonds apart)

ex:

• 
  

double covalent bond

share more than 1 pair of e- (2 pairs of electrons are shared between 2 atoms)

ex:

• 
  

triple covalent bond

3 pairs of e- shared between 2 atoms, triple bonds have the HIGHEST dissociation energy (ability to break the bonds apart)

ex:

• 
  

rules for covalent compounds

• 2 or more nonmetals

• part 1- name stays same

• part 2- ending for all is -ide

• add prefixes

prefixes

• 1 - mono

• 2 - di

• 3 - tri

• 4 - tetra

• 5 - penta

• 6 - hexa

• 7 - hepta

• 8 - octa

• 9 - nona

• 10 - deca

hydrogen bonding

H - O, H - F, & H - N have a strong polar bond (still only 5% of the strength of an covalent bond), creates hydrogen bonds that “stick: molecules together, water is best ex

*water is a liquid at room temp because of hydrogen bonds

hydrates

chemical compound that contains matter molecules incorporated into crystal structure, with # of water molecules being a fixed ratio (when water is evaporated out of a hydrate it is called anhydrous)

ex:

practice

*dont reduce them

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more practice from packet

ex:

• 
  

acids

formula starts with H, special type of ionic compounds, cation always = H⁺¹

*all acids end with -ic & -ous

monatomic

means one atom, anion is a single element of PT

• HF = hyrdo fluor ic (start with hydrogen, 2nd from front of PT)

polyatomic

means many atoms, anion is a polyatomic ion from common ion list

• HCN= H⁺¹ CN⁺¹ = -ide: cyanic acid (2nd from back of PT)

• HNO₃= H⁺¹ (NO₃)⁻¹ = -ate: nitric acid

• HNO₂= H⁺¹ (NO₂)⁻¹ = -ite: nitrous acid *remember sprite is delicous

practice

ex:

• HCI

• 
  

more practice from packet

ex:

• 
  

metallic bonds

metals are bonded together, caused by attraction between closley packed cations & free-floating VE (“sea of electrons”), form a cubic shape

characteristics:

• good conductors

• malleable (cations slide away from eachother, p+ are bonded together & bonds are flexible)

• ductile (form into wires)

• shiny

alloys

combination of more than one metal (properties can often be superior than their component elements, fix natural weaknesses of pure metals

ex:

• brass- Cu + Zn

• bronze- Cu + Sn

• steel- Fe + C

polar vs nonpolar covalent bonds - paulings electronegativity scale

*electronegativity- ability of an atom to attract e-

electronegativity difference:

• (0 - 0.4) - nonpolar covalent (symmetrical) equal sharing, no charge separation

• (0.5 - 1.8) - polar covalent (asymmetrical) unequal sharing, charge separation (+ & - ends)

• (1.9+) - ionic (positive & negative charges / electron transfer)

electron transfer- fully positive and negative charges

polar, nonpolar, or ionic?

Na & Br

polar, nonpolar, or ionic?

N & Br

polar, nonpolar, or ionic?

N & H

polar, nonpolar, or ionic?

C & F

polar, nonpolar, or ionic?

C & H