Unit 3 pt 2?

what are the main mineral groups

what are the main mineral groups

Oxides, sulfides, sulfates, silicates, halides, carbonates, phosphates, native elements, mineraloids

what are main mineral groups based on

chemical formulas

how are minerals grouped into families

chemical composition

what minerals are classified as oxides

minerals where oxygen is combined with one or more metals

what minerals are classified as sulfates

Minerals where the SO42- ion combines with metals

What minerals are classified as sulfides

minerals that are composed of a metal and sulfur

what mineral class is most important & why

silicates - 25% of all known minerals are silicates - 90% of Earth’s crust is composed of silicates

what is the base of a silicate

4 oxygen ions surrounding a silicon ion

What minerals make up halides

halogen elements: Cl, Br, and F combined with one or more metals

What minerals make up carbonates

minerals where metal cations combine with the polyatomic ion CO32-

what is the dominant base for the phosphate group

Tetrahedron: PO43-

What are native elements

minerals composed of atoms from a single element

what are members of the mineraloid class

ions that lack the necessary crystalline structure to be a mineral

ex. pearl, opal, amber

Silicates

olivine, quartz, feldspar, talc, topaz, mica, pyroxene

sulfates

gypsum

Sulfides

pyrite

halides

halite, fluorite

native elements

elements found naturally on their own - ex. gold

carbonates

calcite

phosphates

corundum, hematite

mineraloids

minerals that were produced from a biological process

what elements are diatomic atoms

Bromine

Iodine

Nitrogen

Chlorine

Hydrogen

Oxygen

Fluorine

what is a diatomic atom

elements that are never found alone in nature - always bonded to either another element or another of itself

what happens to the atoms in covalent bonds

they share electrons

what does a single dash on a lewis structure rep.

a single covalent bond

2 electrons are shared

what electrons bond in covalent bonds and why

the valence electrons bond to achieve the electron configuration of a noble gas

what valence electrons bond

the electrons that are not already paired up

what do 2 dashes on a lewis diagram mean

double covalent bond

2 pairs of shared electrons

what do 3 dashes on a lewis diagram mean

triple covalent bond

3 pairs of shared electrons

what do you need to look out for with triple covalent bonds

negative charges - repellent

what is the order of strength in covalent bonds

single < double < triple

what is the relationship between strength and distance in covalent bonds

the stronger the bond, the shorter the distance between atoms

what theory is used for the shape of molecules

vsepr theory

what does vsepr stand for

valence shell electron pair repulsion (like charges repel)

what is molecular geometry based on

the number of bonds and lone pairs around the central atom

1 bond

linear

2 bonds

linear

2 bonds and 2 lone pairs

bent

3 bonds

trigonal planar

3 bonds and 1 lone pair

trigonal pyramidal

4 bonds

tetrahedral

what types of atoms are always linear

diatomic atoms

how do you determine the shape of more complex compounds

determine the shape of the different central atoms

ex. H-C-C-C-H = shape of the three C’s

properties of minerals

• have a fixed composition

• must be solid, naturally occuring, and inorganic

  • SOME have a set shape ex.silicate = tetrahedral

what happens in polar covalent bonds

electrons are not shared equally between the two atoms

what are the two types of covalent bonds

polar and nonpolar

what happens in nonpolar covalent bonds

electrons are shared equally between the two atoms

what atoms are always nonpolar

diatomic atoms

what is the charge of a nonpolar bond

neutral

what atom has a greater charge in polar bonds

the atom with the stronger pull

what is electronegativity

the pull that a atom has for the electrons of another element within a bond

what is the relationship between DEN and polarity in bonds?

the greater the Difference in Electronegativity, the more polar the bond

what is the formula for DEN

DEN = Highest EN - Lowest EN

what DEN amounts are nonpolar covalent bonds

0-0.5 DEN

what DEN amounts are polar covalent bonds

0.5-1.9 DEN

what DEN amounts are polar ionic bonds

2.0 or greater DEN

what element has the greatest electronegativity

fluorine

what elements in the periodic table have low electronegativity, and lose electrons easily

the bottom left corner, metals: groups 1A-3A

what elements in the periodic table have high electronegativity, and attract electrons easily

top right corner, nonmetals, groups 4A-7A

what group does not have any electronegativity

group 8A (noble gases) - they neither gain nor lose electrons

why are compounds with high DEN ionic

bonds with a high DEN have an unequal sharing of sharing of electrons —> sometimes so much that the bonds become ionic

does the polarity of a molecule affect the polarity of its bonds?

no, a molecule can be polar with polar or nonpolar bonds and vice versa

what do you draw dipoles for

polar or “ionic” bonds

what way do dipoles go

less electronegative element to more electronegative element

what do dipoles indicate

what is happening to the shared elections - electrons are going from the lower EN atom towards the higher EN atom

what is DEN used for

to calculate the polarity for specific bonds in a molecule (bond polarity)

true or false

bond polarity = molecular polarity

false, molecules can have their own polarity

properties of polar molecules

soluble in water

slightly higher melting/boiling points than nonpolar cov.

what shapes are Always polar?

bent and trigonal pyramidal

*both have a lone pair of electrons

what shapes are SOMETIMES polar

tetrahedral, linear, trigonal planar

what has to happen for bonds to be nonpolar

the terminal atoms have to be made of the same element —> makes bond symmetrical

QUESTIONS TO DETERMINE MOLECULE POLARITY
Does central atom have a lone pair of electrons?

1. If yes, molecule is POLAR

2. If no, move to #2

QUESTIONS TO DETERMINE MOLECULE POLARITY

Are all atoms surrounding the central atom the same?

1. If yes, molecule is NONPOLAR

2. If no, move to rule #3

QUESTIONS TO DETERMINE MOLECULE POLARITY

Are any of the bonds polar (DEN)

1. If yes, molecule is POLAR

2. If no, molecule is NONPOLAR