chem 110 midterm 1

Chemistry

The science that tries to understand how matter behaves by studying atoms and molecules

Physical chemistry

Quantitive (reports number data) study of a chemical structure and reactivity using physics.

Organic chemistry

The synthesis of reactions involving compounds containing carbon

Inorganic chemistry

Synthesis of metal based molecules and materials

Analytical chemistry

The development in use of tools for chemical analysis

Biochemistry

Study of chemical reactions in biology

The scientific method

A way to learn that emphasizes observation in experimentation

Observation

Statement using five senses

Hypothesis

Tentative explanation

Experiment

Highly controlled and designed situations to test high

Scientific law

General statement that summarizes what happens in a scientific phenomena

Theory

Explanation on the reason why a scientific phenomenon happened

In scientific notation, a positive exponent gets bigger…..

Resulting in the number getting bigger

Scientific notation negative exponents get bigger

The resulting number gets smaller

When multiplying and dividing…

Answer must have at least amount of SIG figs from equation

When adding or subtracting

Answer must have a least amount of decimal places from equation

Length

Base unit = meter

Symbol = m

Mass

Base unit= gram

Symbol = g

Time

Base unit= second

Symbol =s

Temperature

Base unit: kelvin

Symbol : k

Amount

Base unit= mole

Symbol = mol

Volume

Base unit= liter

Symbol: L

Tera-

Symbol= T

Multiplier = 10^12

Giga-

Symbol= G

Multiplier = 10^9

Mega-

Symbol = M

Multiplier = 10^6

Kilo-

Symbol= k

Multiplier = 10³

Centi-

Symbol = c

Multiplier = 10^-2

Milli-

Symbol: m

Multiplier: 10^-3

Micro-

Symbol = μ

Multiplier = 10^-6

nano-

Symbol= n

Multiplier = 10^-9

Squared =

Area

Cubed =

Volume

Density (d)

Mass / volume

matter

anything that has mass and occupies space (has volume)

atoms

submicroscopic particles present in all matter

compounds

arrangements of atoms in specific geometries

solid

• atoms and molecules are in close contact

• no translational motion (can vibrate)

• fixed volume, incompressible, does not expand

• fixed shape

Liquid

• close contact

• have translational motion

• fixed volume

• variable shape

gas

• vary far apart particles

• translational motion

• compressible

• variable volume, shape, can expand

Crystalline solid

long-range order between atoms or molecules

regular spacing between molecules, light can penetrate

amorphous solid

no long-range order

ex: rubber, plastic

Physical property or change

property or change in which the atomic and molecular compositions does not change

physical property

property that a substance has w/o changing its chemical composition

Chemical property

by changing its chemical composition

physical change

change in which a chemical reaction doesn’t occur

• ex: cutting/tearing a piece of paper

• ex: (phase changes) solid water → liquid water

  • Require heat or release heat

Chemical change

a chemical reaction does occur

• indicators of chem change

  • Change in color (iron nail rusts)

  • Change in smell (paper vs burnt paper)

  • Change in texture ^^^

  • Absorption or release of heat 

    • ex: cold packs absorb heat from surface

law of conservation of mass

mass is neither created or destroyed

matter

has mass and occupies space (volume)

energy

the capacity to do work

work

the result of force acting a distance

law of conservation of energy

energy is neither created nor destroyed.

kinetic energy

E of movement

potential energy

E associated w/position

electrical energy

E of the flow of electrical charge (flow of electrons and ions)

thermal energy

E is associated with the movement of atom and molecules within a substance

chemical energy

E associated with chemical bonds

Calorie

The amount of E required to increase (+) the temperature of 1 g of water by +1°C

exothermic process

process that emits energy to the surrounding, can be for physical process or chemical

surrounding gets hotter

ex: condensation (physical)

endothermic process

process that absorbs E from surroundings

temperature

measure of thermal energy movement of atoms and molecules within substance

heat

the transfer of thermal E from a hot object to a cold object

specific heat capacity

the amount of energy required to apply to increase the temperature of 1 g of a substance by +1°c

The Atomic Theory

1. Each element is composed of tiny indestructible particles called atoms

2. All atoms of a given element have the same mass and properties

3. atoms combine in simple whole number ratios (no decimals)

J.J. Thomson (1856-1940)

proposed the idea of an electron

• negatively-charged, smaller than atoms, positive charge

if atoms are neutral and have electrons…

then they must have a positive charge

electrons

negatively charged fundamental particles

plum pudding model

J.J thompson

the atom is a loose sphere of positive charge, which is small dense, electrons are in plum

Rutherford Gold Foil Experiment

Disproved the plum pudding model

1. a very strong stream of alpha particles was shot at a foil

2. most α particles went straight through

3. 1 out of 20000 particles was deflected or bounced back

   1. α particles hit something dense and positive

α (alpha) particles

small positively charged particles

Conclusion from gold foil experiment

A positive charge is not loose, dense + concentracted in center mostly empty space because most α went through.

If the plum-pudding model were true

the α particles would have glided right through

Modern theory of the nuclear model of the atom

1. most of the mass of the atoms and all of its positive charge are contained in its center called the nucleus

2. most of the atoms volume is empty space through which the electrons are dispersed

3. if atom is neutral (overall charge is 0) # of protons = # of electrons

Nucleus

dense center that contains positive particles called protons and neutral particles called neutrons

The atoms nucleus

makes up 99% of the mass of the atom but less than 5% of the volume

Protons

mass (kg) 1.6762×10^-27

mass (amu) 1.0073

neutrons

mass (kg) 1.67493×10^-27

mass (amu) 1.0087

electrons

mass (kg) 0.00091×10^-27

mass (amu) 0.00055

The nature of electrical charge

• protons and electrons have electrical charge

• positive and negative charges attract

• same charges repel

• positive and negative charge cancel

elements are defined by their…

atomic number (z), # of protons

atomic number (z)

number of protons

chemical symbol

an abbreviation of their name

Average atomic mass

weighted average of all isotopes in an element

element

pure substance made of 1 type of atom

• atoms of the same element out defined by their atomic number

• all atoms of an element can have same number of protons

Dmitri Mendeleev

noticed groups of elements had similar properties

arranged the period table in order of increasing mass of elements

Periodic law

when elements are placed in order of increasing mass, chemical properties will recur periodically

Metals

left side of the periodic table

-shiny often solid at room temp

-room temp

-conductive

-lose electrons in reaction

non metals

right side of the table

-no conductivity

-gain electrons in a reaction

Metalloids

zig zag spliting the dif. types of metal

-intermediate conductivity

Main group elements

elements in which we can predict their ionic charge

transition elements

Elements cannot predict ionic charge (middle + block under)

period (row)

elements placed in order of inc mass

have no chemical relationship

Group

each column in period table

element within group have similar chemical properties

Noble gases

He,Ne,Ar,Kr, Xe

8A/18

non reactive gases

Alkali metals

Li, Na, K, Rb, Cs

1A/1

Water reactive metals

Alkaline earth metals

Be, Mg, Ca, Sr

2A/2

exothermic reaction w/ water

Halogens -ine

F, Cl, Br, I, At

17/7A

solids all toxic

ion

atom of the same element (proton # is the same) within more or less electros than protons

Ion Charge

e = # of protons - # of electrons

Cation

positively charged ions, loses electrons (must end in 0)

Metals always become cations

Protons will never change

anions

negatively charged ions

Nonmetals become anions in reactions