chemistry taks review fast track. density density = mass volume d = m v
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Chemistry TAKS Review
Fast Track
Density
Density = mass volume
D = M V
Math Tip for Density
D =
M V 1
Cross Multiply
Buoyancy
Buoyancy
• The force that acts on objects immersed in or floating on a liquid
Photo from: http://www.seed.slb.com/en/scictr/watch/bathroom/duck.htm
Buoyancy
• Buoyancy is related to floating• an object in a liquid is buoyed up (pushed up) by a
force equal to the weight of the liquid the object displaces (pushes aside). This is known as Archimedes’ Principle.
Photo from: http://www.seed.slb.com/en/scictr/watch/bathroom/duck.htm
Viscosity
Viscosity
• Viscosity is the resistance of a liquid to flow
• If a liquid flows slow, it is viscous, or has a high viscosity
Objective 4 - (I.7D)
Periodic Table of the Elements
• An organized table of all the known elements
Atomic Number = Number of Protons
Groups• vertical columns
• contains elements with similar chemical properties
• EX: Li, Na, K
Periods• horizontal rows
• EX: K, Ca, Sc
• Staircase = Metalloids (metal/non-metal combo)
• Right side + Hydrogen = Non-metals
• Left side = Metals
Transition Metals
• Groups 3-12 are called transition metals
Alkali Metals
• Group 1 (IA)
• Very reactive
Valence Electron: Outer Electron
Na
Number of valence electrons represented by the roman numerals
Note this on your periodic table
Valence electrons
• Every element wants 8 valence electrons to be stable
• Elements will lose or gain electrons (which ever is easier) to become stable
Predict if an element will lose or gain electrons? How many?
Charges
• When electrons are gained or lost, a charge is formed
Na1+
Note this on your periodic table
1+
2+ 3-3+
0
2- 1-
Charges
Noble Gases• Group 18 (8A)
• Very stable & will not lose or gain electrons
• Unreactive
Writing Formulas
To make an ionic compound, the charges must cancel out
1+
2+ 3-3+
0
2- 1-
Charges
Goal: Cancel out the charges
Example:Magnesium + bromine
Mg+2 Br-
I need two bromines to cancel out with 1 Mg
+ -+ -
MgBr2
Br
Criss Cross Method
2 1+ -Mg
Criss Cross Method
MgBr2
Criss Cross Method
3 2+ -Al SO4
Criss Cross Method
Al2 SO4 3( )
Al2(SO4)3
AlAl
o
o
So
o
o
os
oo
o
o
s
o
o
SO4
Physical Changes
More Examples– Cutting– Breaking apart
Law of Conservation of Mass
Mass can not be created or destroyed
Using the Law of Conservation of mass
2H2 + O2 2H2O
H2O(s) H2O(l)
C + O2 CO2
100 grams 50 grams ?150 grams
32 grams 32 grams
60 grams20 grams ?40 grams
Balancing Equations
A reaction must be balanced to obey the law of conservation
of mass
• Non-balanced Reaction
H2 + O2 H2O
• Balanced Reaction
2H2 + O2 2H2O
How to balance a reaction
• Step one: list all the element symbols under the arrow of a reaction
H2 + O2 H2O
HO
How to balance a reaction
• Step two: count how many of each atom you have on each side of the reaction
H2 + O2 H2O
HO
2 22 1
Coefficients
• Numbers that are placed in front of a compound/molecules in a reaction
How to balance a reaction
• Step three: add coefficients to the compounds to help make each element even on both sides
H2 + O2 H2O
HO
2 22 1
42
422
The reaction
H2 + O2 H2O22
2 1
Balance Me!
___ XeF2 + ___ H2O __ Xe + __ O2 + __ HF
XeF
1 12 14
2
2
24 H
O1 2
2
2
22
22
4
4
4
Ions
in solution
Objective 4: IPC 9BTSW relate the concentration of ions in a
solution to physical and chemical properties such as pH, electrolytic behavior, and
reactivity
• Distilled water is pure water. It has no ions in it at all.
• An ion is any substance that has a charge. A charge is indicated by a + or - sign.
• Ions in solution (dissolved minerals) can conduct electricity.
Litmus Paper
Aci ase Re lueBD
• More solute will result in a boiling point elevation (increase) and freezing point depression (decrease)
• Why do people put salt on icy roads?
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