Chemistry Honors Semester 1 final Exam

Matter

Anything that has mass and can take up spaceCan be solid, liquid, gas, or plasmaCannot be created or destroyed, but can change form

Mass

A measure of the amount of matter in an objectUnits include g, mg, and kg

Solids

Definite shape, definite volume

Liquids

No definite shape, definite volume

Gases

No definite shape, no definite volume

Physical Properties

Observable with the sensesColor, shape, mass, length, smell, specific heat, odor, and phase changes

Chemical Properties

Indicates how something reacts with a substanceThe ability of iron to rust and the flammability of rubbing alcohol

Extensive

Depends on the amount of matter presentMass, volume, and length

Intensive

Not dependent on the amount of matter presentTemperature, density, boiling point, and electrical conductivity

Physical Changes

* A Change in matter that does not involve a change in the composition of individual substances
* Does not produce a new substance
* Ex. A paper ripping, melting ice, crushing potato chips, dissolving salt, and evaporation

Chemical Changes

* A change in matter that does involve a change in the composition of a substance
* Always produces a new substance
* Burning paper, rusting metal, and decaying of a dead mouse

Pure Substances

Matter with the same composition throughoutElement or compound

Mixutre

Combination of two or more substances in which each substance keeps its unique set of propertiesCan be operated into two or more pure substances

Elements (Pure substance)

Simplest form of matter that cannot be broken down in smaller substances

Compounds (Pure Substances)

Chemical combination of two or more elements joined together in a fixed proportion

Heterogenius mixture

A mixture that has multiple phasesIndividual substances can clearly be seen in the mixture and are not uniformly distributed

homogenous mixture

A mixture that has one phase; substances are evenly distributedThere is a constant composition throughout

Five different indicators of chemical reactions

Color changePrecipitate formedGas producedOdor changeEnergy change

Reactants

Left side of the arrow

Products

Right side of the arrow

Exothermic

Heat is lost; energy is given off; feels warmerEx. Hand warmer, charcoal burning, and dilution of acids

Endothermic

Heat is gained; energy is taken in' it feels coolerEx. Photosynthesis and baking

There can be energy / heat change without a chemical change

Ex. Boiling water

Law of Conservation of Mass

Matter is not created nor destroyed in any chemical or physical change

Parts of a solution

Consists of Solute and Solvents

Solute

Substance being dissolved

Solvent

Substance that dissolves the solute

Phase changes

Substances change phases by adding or subtracting energy

Melting / Freezing

* Occurs when a substance changes from a solid to a liquid or from a liquid to a solid
* Melting of ice and freezing of water both occur at 0 degrees C

Boiling / Condensing

* Occurs when a substance changes from liquid to gas or from gas to liquid
* Water boils and steam condenses at 100 degrees C

Sublimation

* Occurs when a substance changes directly from solid to gas
* Dry ice (solid CO2) and iodine sublime

Alloys

A solid solution usually made up of two ore more metals

Periods

* Horizontal rows


* 7
* Each represents a new energy level

Groups

* Vertical columns
* 18 groups
* Elements within have similar properties

Metals

* Left of stair step


* Conduct heat and electricity well
* Shiny, malleable, and ductile
* Generally Solid

Nonmetals

* Right of stair step
* Doesn't conduct heat and electricity well
* Lack Luster; brittle
* Many are gasses at room temperature
\*\*Hydrogen is a non metal

Metalloids

* Along stair step
* B, Si, Ge, As, Sb, Te
* Have properties of both metals and nonmetals
* Some are semiconductors

Qualitative

Descriptive

Quantitative

Measured, numeric

Meter (m)

distance

Kilgram (kg)

Mass

Second (s)

Time

Ampere (A)

Electricity

Candela (Cd)

light

Mole (mol)

Amount of a substance

Kelvin (K)

Temperature

Kilo

10³

Deci

10¹

Centri

10²

Milli

10⁻³

Micro

10⁻⁶

Nano

10⁻⁹

Pico

10⁻¹²

Volume

Si Unit m³Liter (L)

Density Units

Ratio that compares the mass of an object to its volume

Pressure

Pascal

Energy

Joules

What is the difference between mass and weight?

Weight is a measure of the gravitational pull on an object. It relies on the gravity. Mass doesn't.

Density

The ratio of an object's mass to it's densityD = M/V

Explain and use the equivalencies among L, mL, 1 cm3, and 1 dm3

1 L = 1 dm31 cm3 = 1 mL

Accuracy

Refers to the closeness of a measurement to the actual value of the quantity

Precision

The agreement between results of measurements of the same quantity, made the same way; ability to reproduce results

Percent Error

how close experimental data is to actual values** Measured

What is the purpose of sig figs?

Explain the purpose of using sig

Rules of Significant Figures

1. All non-zero digits are always significant

* 467.2 (4 sig-figs)


2. Zeros appearing between nonzero digits are significant

* 605.08 (5 sig-figs)


3. Zeros appearing before the first nonzero digit are not significant

* 0.0025 (2 sig-figs)


4. Zeros at the end of a number and to the right of a decimal point are significant

* 16.00 (4 sig-figs)
* 320,000.00 (8 sig-figs)
* 0.00250 (3 sig-figs)


5. Zeros at the end of a number without a\` decimal point are not significant

* 215,000 (3 sig-figs)

Rounding Sig Figs

When the number being dropped is a five, round to the even number

addition and subtraction sig figs

Answer must have the same number of digits to the right of the decimal as the number with the fewest

multiplication and division sig figs

Answer can have no more sig-figs than the measurement with the fewest sig-figs

Democritus

* Believed the world is made up of small indivisible particles called atoms and empty space
* Ideas based on observations

Dalton

* Law of Multiple Proportions: if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers


* Modern Atomic Theory

Thomson

* Using cathode ray tubes, he discovered electrons
Determined...


1. Electrons are negatively charged particles
2. All electrons are identical
3. The charge to mass ratio using deflection of rays
Plum Pudding Model of Atoms

* The atom is a sphere of positive matter in which negative electrons are embedded

Milikan

* Oil drop experiment
* Discovered the charge of an electron
* Charge of an electron is -1
* Discovered the mass of an electron
It is 1/1840 of a proton
It has a mass of 0 amu (atomic mass unit)

Rutherford

\- Performed the Gold Foil Experiment \n \*\*Alpha particles were shot at a thin sheet of gold foil \n --Conclusions from Gold Foil \n The atom is mainly empty space \n The atom contains a small, dense, positively charged core called the nucleus \n Predicted the existence of neutrons

Dalton's Atomic Theory

\-- All elements are composed of small, indivisible particles called atoms

\-- Atoms of the same element are identical; atoms of different elements are different

\-- Atoms combine in simple whole-number ratios to form compounds

\-- Chemical reactions occur, but atoms are never changed into atoms of another element b. Changes:

\--Atoms of the same element may be different (isotopes)

\--Atoms can be divided into subatomic particles

Protons

Positively charged \n Inside the nucleus \n Contribute to atomic mass \n Determine the atomic number \n Never gained or lost

Neutrons

Neutral charge (no charge) \n Inside the nucleus \n Contribute to atomic mass \n Never gained or lost

Electrons

Negatively charged \n Outside the nucleus \n In different energy levels; each row on the periodic table is a new energy level \n Do not contribute to atomic mass \n Gained, lost, or shared in bonding

What are isotopes?

Elements that contain the same number of protons but a different number of neutrons \n \*\* Example: C-12 and C-14 both have six protons and six electrons, but C-12 has six neutrons while C-14 has eight neutrons \n C-12: 12/6 C \n C-13: 13/6 C \n C-14: 14/6 C \n Look at bottom # to match isotopes

Atomic Number

* Equal to the number of protons
* Identifies the element
* Is the whole number on the periodic table
* Atomic number = number of protons = number of electrons

Atomic Mass Number

Atomic Mass Number

* Equal to the atomic number/number of protons + the number of neutrons
* Whole number not shown on periodic table

Protons

Equal to Atomic Number

Neutrons

Equal to mass number

Electrons

Equal to protons

Calculate the average atomic mass of an element based on the abundance of its stable isotopes

Average Atomic Mass

Groups on periodic table

vertical columns

Periods on periodic table

horizontal rows

Metals on periodic table

* Left of Stair step
* Usually solid at room temperature
* High luster, malleable, ductile
* Good conductors of heat and electricity

Nonmetals on periodic table

* Right of stair step
* Poor conductors of heat and electricity
* Not malleable or ductile
* Little or no luster

Metaloids on periodic table

* B, Si, Ge, As, Sb, Te


* Some characteristics of metals and nonmetals
* Solids at room temperature
* Less malleable than metals
* Semiconductors of electricity

Cations

\n Positively charged ions. Always metals, are always positive and always come first in formula \n - Lose Electrons when forming bonds

Anions

Negatively charged ions. Always nonmetals always come second

Ionic Compounds

* metal + nonmetal (one element has a positive oxidation number, the other has a negative oxidation number)
* Bond formed by transferring electrons
* Labeled as formula units (ex. 1 formula unit of NaCl)

Molecular compounds

* nonmetal + nonmetal (both elements have a negative oxidation number)
* Bond formed by sharing electrons
* Labeled as molecules (ex. 1 molecule of H2O)

Ammonium

NH₄ +1

Cyanide

CN 1-

Peroxide

O₂²⁻

Carbonate

CO₃²⁻

Chlorate

ClO₃ -

Nitrate

NO₃⁻

Phosphate

PO4 3⁻