Transcript taks review - Fort Bend ISD

TAKS REVIEW
CHEMISTRY
Scientific Method
Using Data Tables
THE ATOM
• For any element:
• Number of Protons = Atomic Number
• Number of Electrons = Number of Protons
= Atomic Number
• Number of Neutrons = Mass Number Atomic Number
KRYPTON
• For krypton:
• Number of Protons = Atomic Number = 36
• Number of Electrons = Number of Protons =
Atomic Number = 36
• Number of Neutrons = Mass Number - Atomic Number
= 84 - 36 = 48
ISOTOPES
• Atomic number is the same, mass
number is different
• Difference in mass is due to
NEUTRONS
• Krypton-84: 36 protons, 48 neutrons
• Krypton-83: 36 protons, 47 neutrons
IONS
• Ions: atom loses or gains ELECTRONS
Metals: lose electron, become positive
(Na+ Ca2+ Al3+)
Non-metals: gain electrons, become
negative (F- O2- N3-)
• Number of electrons lost or gained
determined by position in periodic table
• PROTONS STAY THE SAME IN
IONS AND ISOTOPES
(change number of protons, change
the element)
Matter
Anything that takes up space and has
mass
In reactions matter is conserved: cannot
destroy or create matter (atoms)
Just re-arrange the atoms
Matter Flowchart
Non-uniform
Uniform
Solutions
Mixtures
Bonding
• Ionic:
Made up of ions (+ and -)
Metal/non-metal
Solid, crystal compounds
Lattice structure
Higher boiling/melting points
Ionic Bonding
Bonding
• Covalent
Sharing of electrons
Non metal/ non metal
Gases, liquids (some solids)
Lower boiling/melting points
Covalent Bonding
BONDING
• Both bonding types involve valence
electrons
• Valence electrons determined by
position on periodic table
• Atom wants configuration of noble gas
elements (full outer shell of electrons)
Metallic bonding
• Electrons are shared by atoms in metals
– account for properties of metals:
conductivity, malleable, ductile
WATER
• Water has a covalent bond
• Electrons are not evenly shared,
resulting in slight charge
• POLAR Compound (meaning uneven
charge)
• Oxygen slightly negative, hydrogen
slightly positive
WATER
• Hydrogen bonding occurs between
water molecules
• Gives water unique properties
– Good solvent (universal solvent)
– Higher boiling temperature (when
compared to other molecular compounds)
– Solid is less dense than liquid (ice floats)
Water
pH
• Measure of
hydronium
concentration in
water
• Measure for acid
and bases
Properties of Matter
• Physical: can be observed or measured
without changing the identity of the
substance
– Color
– Density
– Hardness
– Melting/boiling points
Properties of Matter
• Chemical: ability of substance to
undergo a change that transforms it into
a different substance
– Reacts with water
– Explodes in air
Changes
• Physical: doesn’t change identity
– Melting/freezing
– Boiling/condensing
– Dissolving
– Pounding
– evaporating
Changes
• Chemical: changes identity
– Rust
– Explode
– Reacting
• Signs of chemical changes:
– Bubbles, precipitate (solid forming), energy
released or absorbed (heat or light)
Rock Cycle
Sample questions
When a 10% hydrochloric acid solution is
heated in an open test tube, the test tube
should always be pointed —
A
so bubbles are visible
B
at a 180° angle from the flame
C
toward a ventilated area
D
away from nearby people ***
Sample questions
5 The picture shows a model of the
element
A fluorine
B helium
C beryllium ***
D oxygen
Photosynthesis
Light energy
6CO2 + 6H2O  C6H12O6 + 6O2
Respiration
C6H12O6 + 6O2  energy + 6CO2 +6H2O
Oxygen (O2) is an example of —
A an alloy
B a molecule ***
C a salt
D a mixture
Photosynthesis
Light energy
6CO2 + 6H2O  C6H12O6 + 6O2
Respiration
C6H12O6 + 6O2  energy + 6CO2 +6H2O
To produce 4 molecules of sugar,
a plant needs —
F 6 molecules of hydrogen
G 12 molecules of ATP
H 18 molecules of water
J 24 molecules of carbon dioxide ***
Which of the following will allow measurement of
a liquid’s volume with the greatest precision?
A 50 mL cylinder graduated in 1 mL increments
*** B 100 mL cylinder graduated in 0.5 mL
increments
C 100 mL cylinder graduated in 1 mL increments
D 200 mL cylinder graduated in 5 mL increments
• Which of the following pieces of equipment would be
most appropriate for measuring the volume of a
marble?
****
In the rock cycle, which of these is a
chemical change involved with the
formation of igneous rocks?
F Compression of sediments
G Heat loss from lava
H Subduction of plates
J Formation of minerals ****
What characteristic of water remains the
same no matter what is dissolved in it?
A The ratio of hydrogen to oxygen
****
B The ability to refract light
C The hydroxide ion concentration
D The freezing temperature
What are the coefficients that will balance
this chemical equation?
A 2, 1, 1
B 3, 4, 2
C 2, 2, 1 ****
D 4, 3, 2
Solubility Rules
1. All sodium, potassium, and ammonium salts are soluble.
2. All silver, lead, and mercury salts are insoluble.
3. All carbonates, sulfides and hydroxides are insoluble.
4. All sulfates are soluble except calcium sulfate and barium
sulfate.
Which of the following salts has the greatest solubility in
water at 25°C?
F CaCO3
G FeS
H HgCl2
J
KClO4 ****
As temperature drops to the dew point,
clouds form in the atmosphere, and dew
forms on ground surfaces. A scientist
proposes that adding more water
molecules to the atmosphere will change
the dew point. This proposal is —
F an invalid observation
G a valid hypothesis ****
H an invalid problem
J a valid conclusion
Laboratory equipment is cleaned and properly
stored after use primarily so that —
A chemical products can be measured and
recorded as data
B time is saved in setting up the next
experiment
C toxic materials can be kept in the laboratory
D the possibility of contamination in the
laboratory is minimized *****