chemistry1

chapter 1-3

Law of Conservation of Matter

matter cannot be created or destroyed (in any chemical/physical reaction)

Mass v. weight

Mass measures the amount of matter in an object

Weight is the force of gravity acting on an object

(density \= mass/volume)

physical property

a characteristic that can be observed or measured without changing the identity of the substance

chemical property

a property of matter that describes a substance's ability to participate in chemical reactions

solid

definite shape and volume

liquid

definite volume (indefinite shape)

gas

indefinite shape and volume

sig fig rule for addition and subtraction

least number of decimal places (number after the decimal)

sig fig rule for multiplying and dividing

least number of sig figs

formula for mass

density x volume

Homogeneous mixtures (solution)

a mixture that is the same throughout; salt water, mouthwash, ALL alloys

Pure substances

elements and compounds; chemical reactions occur between them

What are elements (pure substances)

oxygen; hydrogen; iron

what are compounds

water; table salt; ammonia

Examples of heterogeneous mixtures

pizza; salad dressing; chocolate chip cookies; solid waste dump

Examples of physical properties

density, color, hardness, melting and boiling point, conductivity (accompanies change in its chemical composition)

Examples of chemical properties

flammability, toxicity, acidity, reactivity, and heat of combustion

extensive property

depends on the amount of matter in a substance

examples of extensive property

mass, volume, heat

intensive property

does not depend on the amount of matter

intensive property example

density and temperature

SI unit of length

meter; m

SI unit of mass

kilogram; kg

SI unit for time

second; s

SI unit for temperature

kelvin; k

SI unit abbreviations

mksk

SI unit for volume

cubic meter ; m^3 (others are L --\> dm^3; ml --\> cm^3)

SI unit for density

kilogram per cubic meter ; kg/m^3

SI unit for density (SOLIDS, LIQUIDS)

gram per cubic centimeter; g/cm^3

SI unit for density (GASES)

gram per liter; g/L

precise measurement

similar results

accurate measurement

result close to true/correct/accepted value

Dalton's Atomic Theory

matter is made of atoms, atoms of different elements have different properties, atoms of same elements have same mass

Dalton's Atomic theory (2)

two elements make a compound (number of atoms of each of its elements are always present in the same ratio), atoms cannot be destroyed or created from chemical changes

Law of definite proportions

given compound will always contain the same proportion of elements by mass

Law of multiple proportions

if two elements combine in different small, whole number ratios, the compounds are different

Charge to mass ratio

1.76 x 10^8 C/g (thomson)

Millikan's oil drop experiment

determined charge of electron

Thomson's model

sphere of positive charge where negative charges are embedded)

Ernest Rutherford

discovered the nucleus (gold foil experiment)

James chadwich

discovered neutron

Atomic number

number of protons in nucleus ("Z"; for neutral atom protons equal electrons; determines identity of atom)

Mass Number

number or protons plus number of neutrons ("A"; number of neutrons \= A - Z)

When are atoms neutral

sme number of charged protons and electrons

How to calculate atomic charge

number of protons - number of electrons (atoms acquire charge by losing or gaining electrons)

Cation

atom that loses one or more electrons (positive charge; right side of symbol)

anion

atom that gains one or more electrons (negative charge; right side of symbol)

Isotype

atoms of the same element with different number of neutrons in their nuclei (most elements exist naturally as a mixture of two or more isotope)

Molecular formula

subscripts that tell how many there are

structural formula

same information as molecular formula but shows connections between atoms in the molecule

Binary compound

made of two elements

Binary ionic compounds

composed of a metal and a nonmental

binary covalent compounds

composed of two nonmetals or metalloids

Metals that form one type of ion

groups 1, 2, and all of 13 (Except TI)

metals that form more than one type of ion

all transition metals (except Ag/Zn)

James maxwell

Light is a wave we can see

wavelength

peak to peak

amplitude

(vertical) distance from midline to peak

frequency (v)

the number of complete wavelengths that pass a point in a given time

speed of the wave

wavelength x frequency

c\=

2.988 x 10^8 m/s

v \=

frequency/Hz/s^-1

As the wavelength \____ the frequency \___ and vice versa

increases, decreases

Photoelectric effect

irradiation of clean metal surface with light causes electrons to be ejected from the metal

Electromagnetic energy is

quantized

what does each emission line consist of

single wavelength of light

Each element displays

its own unique set of lines

How do you produce line spectra

exciting a gas at low partial pressure using an electrical current/heating it

What did Niels Bohr do in 1913

explain the emission spectra for hydrogen

Bohr model (visual)

nucleus with an electron circling around it (electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits)

What did bohr's model do with hydrogen atom

energy levels were consistent with the hydrogen emission spectrum

Change in energy

2.179 x 10^-18J (1/n21-1/n22)

Bohr model limitations

unable to extend theory to next simplest atom; does not account for electron/electron interactions in atoms with more than one electrons

Energies of electrons are described by/quantized

quantum numbers

Discrete energies (lines) in the spectra of elements result from

quantized electronic energies

De Brogile (1925)

Treats the electron as a circular standing wave

De Brogile Formula

(Debrogile) wavelength \= h/mv

De Broglie "h"

planck's constant

De Broglie "m"

particle mass

De Broglie "v"

particle velocity

De Brogile allows the calculation of

a "wavelength" of an electtron (or any particle or object) of mass m and velocity v

Heisenberg uncertainty principle (1927)

stated it's impossible to know exactly (precisely) where an electron is and what path it follows

Schrodinger (1926)

quantum mechanical model; focuses on the wavelike properties of the electron

Wavefunctions can determine

the distribution of the electron's density (with respect to the nucleus in an tom)

Quantum mechanical model explains

electrons can exist only in discrete energy levels but not between them; energy of an electron is quantized (the energy can be equal only to certain specific values and can jump from one energy level to another but not transition smoothly or stay between these levels)

Principal quantum number - n (or shell number)

describes the size/energy level of the orbital shell and is a positive integer (n\= 1, 2, 3, 4...)

As the value of n increases

the energy increases and the average distance of e from the nucleus increases

atomic orbital

region in atom that an electron is most likely/probable to reside

Angular momentum quantum number - I

defines shape of the orbital (for a given value of n, I\= 0,1,2,3,... n-1)

I\=0

s orbital

I \= 1

p orbital

I \= 2

d orbital

I \= 3

f orbital

n\=1

I\=0 (s)

n\=2

I\=0 (S) or 1 (p)

Orbitals with the same value of I

form a subshell

number of radial nodes in an orbital is

n-I-1