Chemistry Midterm

Sophomore Year

atoms and molecules

all things are made up of...

Law of Conservation of Mass by Antoine Lavoisier

matter is neither created or destroyed during a chemical reaction

scientific law

a concise statement that summarizes the results of many observations and experiments

scientific theory

A well-tested explanation for a wide range of observations or experimental results.

Atomic Theory by John Dalton

A theory stating that all matter is composed of tiny indestructible particles called atoms.

scientific method

A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions. (Starts with observation or prior knowledge.

false

Energy has mass

true

molecules are composed of atoms

test theories

experiments are designed to

hypothesis

A testable prediction, often implied by a theory

infinite

defined numbers have an \_________ amount of significant digits

zero

all non-\_______ digits are significant

sandwich rule

seros between two significant digits are significant (27007)

trailing

\__________ zeros to the right of a decimal point to the right of a significant digit are significant(0.275000)

leading

\___________ zeros to the right of a decimal and to the left of a significant digit are NOT significant (PLACEHOLDER zeros)(0.000875)

ambiguous

zeros to the left of a decimal and to the right of a significant digit are \____________ and should be avoided by using scientific notation (5,000\----\>5.0*10^3)

addition/subtraction

same number of decimal places as the measurement with the fewest decimal places

multiplication/division

the result should carry the same number of significant figures as the factor with the least number of significant digits.

d\=m/v

density formula

molecules

atoms bond to form

amorphous or crystalline

solid matter can be...

amorphous solid

A solid made up of particles that are not arranged in a regular pattern

crystalline solid

A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern

pure substance (elements or compunds)

A substance made of only one kind of unit and having definite properties.

mixture

A combination of two or more substances that are not chemically combined

homogeneous mixture

A mixture in which substances are evenly distributed throughout the mixture

solution

always transparent and sometimes colorless

heterogeneous mixtures

A mixture in which different materials can be distinguished easily

physical change

A change in a substance that does not involve a change in the identity of the substance

chemical change

A change that occurs when one or more substances change into entirely new substances with different properties.

law of conservation of mass

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

physical property

A characteristic of a pure substance that can be observed without changing it into another substance

chemical property

A characteristic of a pure substance that describes its ability to change into different substances

exothermic

releases energy (heat)

endothermic

Absorbs energy (heat)

temperature of matter

measure of the random motion of atoms and molecules that compose matter (rapid movement increases temperature and vice versa)

heat capacity

the amount of heat needed to increase the temperature of an object exactly 1°C

specific heat capacity

the energy required to raise the temperature of one gram of a substance by one degree Celsius

elements

A molecule composed of one kind of atom; cannot be broken into simpler units by chemical reactions.

compounds

2 or more elements chemically combined

energy

the capacity to do word

heat

The energy transferred between objects that are at different temperatures

4.184 joules (J)

1 calorie (cal)

1000 calories

1 Calorie (C)

3.60*10^6 J

1 kilowatt hour (kWh)

electrons

negatively charged subatomic particles

protons

positively charged subatomic particles

neutrons

the particles of the nucleus that have no charge

isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

percent natural abundance

the percentage amount of each isotope of an element in a naturally occurring sample of the element

Dalton's atomic theory

1) all matter is composed of atoms which are tiny, indivisible, marble-like spheres NOT TRUE 2) all atoms of the same element are the same and have the same chemical and physical properties, including atomic mass NOT TRUE 3) atoms of elements, combine in simple, whole number ratios to form compounds TRUE

Thomson's plum pudding model

model of a spherical atom composed of diffuse positively charged matter in which electrons are embedded like raisins in plum pudding (sphere of positive charge studded with electrons) NOT CORRECT

Rutherford's Gold Foil Experiment

Alpha-particles were directed at a thin sheet of gold foil ; most passed through the foil (shows that atoms are mostly empty space), but a few were deflected (atoms have a small region of positive charge, and there must be something small and dense in atom); this led to the discovery of the atomic nucleus

Democritus

Greek philosopher that said all matter is made of tiny particles called "atomos" or atoms

nuclear theory of the atom

A theory stating that most of the atom's mass and all of its positive charge are contained in a small, dense nucleus. Most of the volume of the atom is empty space occupied by negatively charged electrons.

J.J Thomson

discovered the electron

+1

group 1 charge

+2

Group 2

+3

group 13 charge

-1

group 17

-2

group 16

-3

group 15

mass of an isotope

protons + neutrons

100

percent natural abundance should add up to \_____%

Law of Constant Composition

A given compound always contains elements in exactly the same proportion by mass

ionic compounds

a compound composed of positive and negative ions (cations and anions)

empirical formula

a chemical formula showing the ratio of elements in a compound rather than the total number of atoms

molecular formula

actual chemical formula of a particular compound

- a whole number multiplier of empirical formula

structural formula

a formula that shows the arrangement of atoms in the molecule of a compound.

Joseph Proust

who discovered law of constant composition

diatomic molecules

molecules made up of two atoms of the same element

H2, N2, O2, F2, Cl2, Br2, I2

what are the diatomic molecule?

atomic elements

exist in nature with single atoms as their basic units

molecular compounds

two or more nonmetals chemically combined

H2O, C6H12O6, CO2

what are the molecular compounds?

ionic compounds

at least one metal bonded to a nonmetal, the same as polyatomic ions

F.U.s

smallest unit of polyatomic ions

molecule

smallest unit of molecular compounds

positive, negative

name is always \___________ ion name followed by \___________ ion name

ide

monatomic anions end in \______ when naming

ite, ate

polyatomic anions end in \_____ or\______ when naming

mono

1 prefix

di

two

tri

three

tetra

prefix for 4

penta

prefix for 5

hexa

prefix for 6

hepta

7

octa

prefix for 8

nona

prefix for 9

deca

10

hydro \_______-ic

anions ending in ide when naming ACIDS

-ic

anions ending in ate when naming ACIDS

-ous

anions ending in ite when naming ACIDS

H+

acid signifier

formula mass

the mass of a molecule or formula unit in amu

10^3

kilo

hecto

10^2

deca

10^1