Essay: Chemistry: Branches, The Scientific Method, Elements, Compounds and More



Chemistry First Semester Review

Define chemistry and list the branches.

~Chemistry:the branch of science that deals with the identification of the substances of which matter is composed

~the three branches of chemistry are organic chemistry, inorganic chemistry, analytical chemistry, physical chemistry, and biochemistry

List the steps of the scientific method:

~observation

~question

~hypothesis

~form an experiment

~make a conclusion

~share the results

What is a control?

~Control: the group in an experiment that isn’t treated as to compare the results of the treated groups to it

Distinguish between theory and law

~Theory:one or more hypotheses that have been supported through repeated testing.

~Law:Laws are accepted as being universal and are the cornerstones of science

Distinguish between science and technology and give examples of each

~science: the pursuit of knowledge

~technology: to improve the standard of life after creating a product

Distinguish between mass and  weight(include units)

~mass: amount of matter something contains

~weight:measurement of a pull of gravity on an object

Review the metric system

SI unit of length, mass, volume, and temp

~length: meters

~mass: kilograms

~volume: cubic meters

~temperature: kelvins

Define volume:

~amount of space an object occupies

What is a meniscus

~meniscus: the curve on the top layer of a liquid caused by surface tension

How many cm in 321 km? How many m/s is 80.0km/hr?

~32,100,000

Convert 25°C to Kelvins

~298.15 K

Write numbers in scientific notation. 1540000000 and .00000539

~1.54 x10^9

~5.39 x 10^-6

Calculate density if the mass is 55g and the volume is 4.2 cm³.

~p=m/v , 55/4.2=13.10

Distinguish between accuracy and precision

~accuracy: getting something right, but not repetitively

~precision: getting the same thing repetitively, though it may be wrong

List the rules for significant digits.

~non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant.

Distinguish between qualitative and quantitative observation.

~qualitative: physical observations, based on quality of observed substance, non numerical

~quantitative: numerical values

Define matter

~physical substance that occupies space: solid, liquid, plasma, or gas

Differentiate between homo- and hetero-  geneous mixtures ~a homogeneous mixture:mixture with a common composition; the contents are even and mixed well, all samples are identical:salt water

~heterogeneous mixture: does not blend smoothly throughout & the individual substances remain distinct, comp not uniform

What is an element? What is a compound? What is a solution? What is an alloy?

~element: an element is a base unit of a substance that cannot be chemically broken down into simpler substances and are a primary basis of matter.

~compound: anything that is composed of two or more elements; a mixture

~solution:a liquid mixture in which the the solute is uniformly distributed within the the solvent

~alloy: a metal made by mixing two or more metals in order to make it stronger

What is the difference between an atom and a molecule

~atom: single unit, nucleus surrounded by electrons: H, O

~molecule: a substance that is made of multiple atoms. Atoms are connected with single, double, or triple bonds in a molecule: H2O

List physical and chemical properties of matter

~physical properties of matter: color, smell, freezing point, boiling point, melting point, opacity, viscosity and density.

~chemical properties of matter: oxidation, flammability, heat of combustion,

chemical stability, radioactivity.

Give examples of intensive and extensive properties

~intensive: independent on the amount of substance:color, hardness, boiling point, molecular weight and sometimes density

~extensive: dependent on the amount of substance: mass, volume

Describe solids, liquids and gases in terms of volume, shape, and particle arrangement

Describe phase changes (freezing, boiling, melting, condensation, sublimation, deposition)

~phase changes: a point where the substance changes

~freezing point of water: 32°F, 0°C, 273°K(liquid to solid)

~boiling point of water: 212°F, 100°C, 373°K (solid to liquid)

~condensation:gas to liquid

~sublimation: solid to gas

~deposition: gas to solid

~evaporation: liquid to gas

List the physical and chemical changes

~physical: freezing point, boiling point, anything that can be reversed

~chemical changes: rusting, burning, anything that cannot be reversed and changes the chemical composition of an substance

Review history of atomic theory

~John Dalton:proposed modern atomic theory

~Ernest Rutherford:theorized that atoms have their charge concentrated in a very small nucleus, pioneered the Rutherford model of the atom, gold foil experiment

~Law of Conservation of Matter:matter cannot be created or destroyed

~Law of Definite Proportions: Atoms form in whole number ratios, so their proportion by mass will always remain the same

~Law of Multiple Proportions:when two elements are combined to form more than one compound, the weights of the elements that combine are in a ratio of small whole numbers.

What is an isotope

~isotope: variations of an element that are different based on the number of neutrons

What does the atomic number indicate? What does the mass number indicate?

~atomic number: number of protons and electrons

~mass number: atomic mass

Use the periodic table to determine the number of protons, neutrons, and electrons in an atom

~protons and electrons: upper left hand corner

~neutrons: atomic mass – atomic number

Indicate the charge, mass, and location of each subatomic particle

~charge: upper right hand corner

~mass: bottom

~location: right of staircase is nonmetals, left of staircase is metals

List the forces within the atom

~forces within an atom are electromagnetism, strength, weakness, and gravity

What is an atomic emission spectrum

~light that is shone when electricity is shot through an element or when it's viewed through a prism

What is a photon

~A photon is energy associated with electromagnetic radiation (light). Particles that transmit light

What is the ground state of an atom? What is the excited state?

~ground state: lowest energy level for an atom

~excited state:any state of the atom that has more energy than the ground state

What happens when an electron moves from an excited state to the ground state?

~ the electron gives off energy

What shape is an s orbital? The p orbital?

~s: spherical

~p: dumbbell shaped

Give the #of orbitals and the #of electrons in each orbital

~s: 1 orbital, 2 electrons

~p: 3 orbitals, 6 electrons, 8 total

~d: 5 orbitals, 10 electrons, 18 total

~f: 7 orbitals, 14 electrons, 32 total

State the heisenberg uncertainty principle

~one can never simultaneously know the exact position and the exact speed of an object

What is hund’s rule

~every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied

What is the pauli exclusion principle

~ in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.

Write the electron configuration for elements number 8, 18, 26, 82. Show the noble gas notation, orbital notation and the electron dot structure for each

~8(Oxygen); , ,[He]:2s22p4   

~18(Argon); , ,[Ne]3s2 3p6

~26(Iron);,,[Ar] 4s23d6

~82(Lead);, , [Xe] 6s26p2

What was Dmitri mendeleev's you 1contribution? What was moseley's contribution?

~Dmitri Mendeleev:1st periodic table, predicted unknown elements

~Henry Moseley:discovered proton and atomic theory, developed periodic law

How is the modern periodic periodic table arranged?

~the modern periodic table is arranged by increasing atomic number

What is the periodic law

~ periodic law: chemical and physical properties tend to repeat when the elements are arranged by atomic weights

Describe the organization of the periodic table in terms of periods and groups

~ the columns called groups share similar properties

~the horizontal rows called periods increase by atomic number and mass

Identify families 1,2, 3-12, 17, and 18 on the periodic table

~group 1: alkali metals

~group 2: alkaline earth metals

~groups 3-12: transition metals

~group 17: halogens

~group 18: noble gases

~ (group 13 is the boron group, group 14 is the carbon group,group 15 is the nitrogen group and group 16 is the oxygen group)

List 3 properties of metals and nonmetals. Where are they located on the periodic table?what are metalloids? Where are they located?

~metals: high boiling and melting points, good electrical conductors, shiny; all elements to the left of the staircase of metalloids are metals.

~nonmetals: Brittle, poor conductors of electricity, high ionization energy; they are located to the right of the metalloid staircase

~metalloids: semiconductors, look like metals but not the same properties, solid at room temp; their place on the periodic table is the staircase:boron, silicon, germanium, arsenic, antimony, tellurium, astatine

Locate the s, p d , f regions on the periodic table

~s: groups one and two plus helium

~p: groups 13-18 minus helium

~d:  groups 3-12 (transition metals)

~f: lanthanides and actinides (bottom)

Identify the number of valence electrons and oxidation numbers on the periodic table.(main block)

~valence are found by adding the number of electrons on the outer shell, for example, carbon has 4 valence because there are 4 elements leading up to carbon in that period

~oxidation numbers are the numbers at the upper right hand corner of the box that tell you how many electrons are gained or lost till reaching noble gas configuration  

What is the most reactive metal? Most reactive nonmetal?

~the most reactive metal is francium(manmade) and cesium (natural)

~the most reactive nonmetal is fluorine

Which elements are virtually unreactive?

~noble gases are virtually unreactive

Describe the general trends in electronegativity and atomic radius

~top to bottom down a group, electronegativity decreases and ,increases as you move from left to right across a period on the periodic table.

~atomic radius increases up a group and from left to right across a period.

What is an ionic bond? Lost properties of an ionic bond

~a bond between a metal and a nonmetal

~soluble in water, do not conduct electricity, weaker bonds

Describe a crystal lattice

~a regular pattern, showing the positions of atoms, molecules, or ions in the structure of a crystal.

How do atoms form covalent bonds

~ when electrons are being shared between two atoms

~non metal and nonmetal

What is a molecule

~atoms bonded together that are electrically neutral

Distinguish between polar and nonpolar molecules

Both are covalent bonds

~polar:a pair of electrons is unequally shared between two atoms

~nonpolar: two atoms share a pair of electrons with each other

Explain the octet rule

~ atoms tend to bond in a way that each atom has 8 valence electrons which gives them noble gas configuration.

Name and write the chemical formulas for 2 ionic compounds and 2 covalent compounds

~Fe3+ = iron (III) ion (ionic)

~Na+ + Cl- –> NaCl; sodium + chloride –> sodium chloride (ionic)

~PH3 =phosphorus trihydride

~CO = carbon monoxide

What is the stock naming system? Write the formula for copper(II)oxide

~a naming system in which the charges are listen in roman numerals

~ Copper(II) oxide:CuO

List 4 indications that a chemical reaction has occurred

~temperature change

~change in color

~odor

~gas bubbles

~precipitate

Define precipitate

~ a precipitate is a solid form in a solution that forms after a chemical bond

Identify the 5 types of chemical reactions. Find an equation for each type and balance it.

~Synthesis: 2Ca +O2 —–>2CaO

~Decomposition: 2H20 ———>2H2 +O2

~ Single replacement: Zn +H2S ———> H2 + ZnS

~Double replacement: AgNO3 + NaCl ——–>NaNO3 + AgCl

~Combustion: CH4 +2O2 ——-> CO2  +2H2O