Honors Chemistry Midterm Flashcards

SIG FIG

SIG FIG

Rules: All nonzero digits are significant and zeros between nonzero digits are significant

• Ex: 12,000= 2 sig fig

• Ex: .102= 3 sig fig

Units of Measurement

• Mass– kg

• length (distance)-- meter

• Time– second

• Temperature– Kelvin

• Amnt. of substance– mol

• Amnt. of force= grams

Democritus=

came up with idea of atom (atomos)

Dalton=

defines the atom– saying all elements are tiny indivisible particles

J.J. Thomson=

plum pudding model and discovered the electron and that they are negatively charged subatomic particles

Rutherford=

nuclear model of the nucleus

Robert Milikin=

calculated electron mass and charge of electron (oil drop experiment)

Niels Bohr=

developed new atomic model and propped electrons were found only in specific circular paths/orbits around nucleus

Erwin Schrodinger=

developed quantum mechanic model and atomic orbital

Statements of Dalton's Atomic Theory

1. All elements are composed of tiny indivisible particles called atoms

2. Atoms of the same element are identical. [False]

3. The atoms of one element are different from those of any other element. [True]

4. Atoms of different elements can combine with atoms from other elements to form compounds

5. Atoms of one element are never changed into atoms of another element as a result of a chemical reaction

		Properties of Subatomic Particles
Particle	Symbol	Relative Charge	Relative Mass
Electron	e-	1-	1/1840
Proton	p+	1+	1
Neutron	n0	0	1

Finding Protons=

atomic number, same number as electrons

Finding Neutrons=

atomic mass - number of protons

Finding Electrons=

look @ atomic number

Chemistry=

the study of composition of matter and the changes that matter undergoes

Matter=

anything that has mass and occupies space

Atom:

the smallest particle of an element that retains its identity in a chemical reaction, smallest unit of matter

Electron:

negatively charged subatomic particle

Cathode ray:

stream of electrons produced at negative electrode (cathode) of a tube containing a gas at low pressure

Proton: 

positively charged subatomic particle found in nucleus of atom

Atomic Number:

number of protons in nucleus of atom of an element (identifies element)

Mass Number:

total number of protons and neutrons in nucleus of atom

 Isotopes:

atoms of same element that have same atomic number but DIFFERENT atomic masses due to different number of neutrons

Atomic Mass Unit (Amu):

1/12 of the mass of a carbon-12 atom

Atomic Mass:

weighted average of the masses of the isotopes of an element

Neutron:

subatomic particle with NO charge and a mass of 1 amu; found nucleus of atom

Nucleus:

tiny central core of atom and composed of protons and neutrons

Energy level:

the specific energies an electron in an atom or other system can move

Quantum:

the amount of energy needed to move an electron from one energy level to another

Quantum mechanical model:

the modern description, primarily mathematical of the behavior of electrons in atoms

Atomic orbital:

a mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probability of finding an electron

Know tetrahedral shape– methane

Orbital Notation

Ex: Boron

Electron Configuration/ Noble Gas Configuration

Ex: Barium– [Xe] 6s2

Bohr's model:

• Could only explain the spectra of single atoms with one electron

• In model= electrons move around the protons, which are at the center of the atom

• Problem with his model= only explained hydrogen

Aufbau Principle=

in the ground state of an atom or ion, electrons fill subshells of the lowest available energy, then they fill subshells of higher energy

Pauli-Exclusion Principle=

arrows have to be pointing in different directions for orbital notation (opposite spins)

Hund's Rule=

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

Wave Diagram:

(Inverse relationship) If frequency increases wavelength…

decreases 

red=

low energy (long wavelength and low frequency)

violet=

high frequency (short wavelength and high frequency)

Dobereiner's classification system failed=

not all of the known elements could be grouped into triads

By 1700=

13 elements were discovered and isolates by scientists

Dmitri Mendeleev:

arranged the elements according to atomic mass and used the arrangement to predict the properties of missing elements

Alkali:

• 1 valence electron

• 1+ ion

• Low ionization energy

• React violently w/ H₂O to produce explosive hydrogen has and strong base

• Very soft– can be cut w/ a butter knife

Alkaline:

• 2 valence electrons 

• Form 2+ ions

• Low ionization energy

Halogens:

• 7 valence electrons that are TIGHTLY held

• Form 1- anions

• High electron affinity

• Most reactive nonmetals– strong oxidizers

• Composed of diatomic molecules in elemental state

• Low melting/boiling point 

Noble gasses:

• 8 valence electrons (except He= has 2)

• Very stable– seldom form compounds

• Known as inert gasses– very UNreactive

• Low melting/boiling points 

• colorless/ odorless

Atomic radius trend:

• increases going down a group

• As move across period to right the atomic radius will decrease

Ionization energy trend (opposite of atomic): 

• Decreases going down a group 

• As move across period to right– increase atomic radius

Electronegativity trend:

• fluorine= has LARGEST electronegativity (4.0)

• cesium= has LOWEST electronegativity (0.7)

Naming/ Writing Ionic/ Molecular Compounds (REFER TO WORKSHEETS)

• Ex: Name the following ionic compounds: TiBr₃ and Fe(NO₃₎₃

• Ex: Write the formula of the Ionic compound: potassium acetate and copper (1) phosphate

• Ex: Write the molecular compound and tell whether it is ionic or covalent: tetrasulfur dinitride and gallium oxide

• Ex: Name the molecular formula and tell whether it is ionic or covalent: CaSO₄ and Ag₃P 

Be able to Solve % comp problems, empirical formula problems, find molecular formulas from empirical formulas

Metals=

one of a class of elements that are good conductors of heat and electric current; metals= malleable, ductile and shiny

Nonmetals=

element that tends to be poor conductor of heat and electric current; nonmetals generally have properties opposite to those of metals

Metalloids=

an element that tends to have properties that are similar to those of metals and nonmetals

Alkali=

any metal in group 1

Alkaline=

any metal in group 2

Halogen=

a NONmetal in group 7

Noble Gasses=

an element in group 8 (STP blocks are highest occupied energy level)

Electronegativity=

the ability of an atom to attract electrons when the atom is in a compound

Ionization energy=

the energy required to remove an electron from an atom

Atomic radius=

the total distance from an atom's nucleus to the outermost orbital of electrons.

Ionic radius=

the distance between the nucleus of an ion and the outermost shell of the ion.

Periodic Law=

when the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties

Representative Element=

s and p block element

Transition Metal=

the highest occupied s sublevel and a nearby d sublevel generally contain electrons

Inner Transition Metal=

an element in the lanthanide or actinide series; the highest occupied s sublevel and nearby f sublevel of its atoms generally contain electrons;

Ion=

an atom or group of atoms that has a positive or negative charge

Cation=

any atom or group of atoms with a positive charge

Anion=

any atom or group of atoms with a negative charge

VSEPR theory=

valence-shell electron-pair repulsion theory; because electron pairs repel, molecules adjust their shapes so that valence electron pairs are as far apart as possible

Covalent Bond=

a bond formed by the sharing of electrons between atoms

Molecule=

a neutral group of atoms joined together by covalent bonds

Diatomic Molecule=

a molecule consisting of two atoms

Molecular Compound=

a compound that is composed of molecules

Molecular Formula=

a chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of a compound

Unshared Pair=

a pair of valence electrons that is not shared between atoms

Coordinate Covalent Bond=

a covalent bond in which one atom contributes both bonding electrons

Polyatomic Ion=

a tightly bound group of atoms that behaves as a unit and has a positive or negative charge

Hybridization=

the mixing of several atomic orbitals to form the same total number of equivalent hybrid orbitals

Nonpolar Covalent Bond=

a covalent bond in which the electrons are shared equally by the two atoms

Polar Covalent Bond=

a covalent bond between atoms in which the electrons are shared unequally

Polar Molecule=

a molecule in which one side of the molecule is slightly negative and the opposite side is slightly positive

Dipole=

a molecule that has two poles, or regions, with opposite charges

Van der Waals Forces=

the two weakest intermolecular attractions—dispersion interactions and dipole forces

Dipole Interaction=

intermolecular forces resulting from the attraction of oppositely charged regions of polar molecules

Dispersion Force=

attractions between molecules caused by the electron motion on one molecule affecting the electron motion on the other through electrical forces; these are the weakest interactions between molecules

Hydrogen Bond=

attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom

Binary Compound=

a compound composed of two elements; (Ex: NaCl)

Monatomic Ion=

a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons

Molar Mass=

a term used to refer to the mass of a mole of any substance

Chemical Equation=

an expression representing a chemical reaction;

Skeleton Equation=

a chemical equation that does not indicate the relative amounts of reactants and products

Catalyst=

a substance that increases the rate of reaction by lowering the activation-energy barrier

Coefficient=

a small whole number that appears in front of a formula in a balanced chemical equation

Balanced equation=

each side of the equation has the same number of atoms of each element

Combination/Synthesis Reaction=

a chemical change in which two or more substances react to form a single new substance

Decomposition Reaction=

a chemical change in which a single compound is broken down into two or more simpler products