Intro to Chemistry

Elements are
Pure substances that cannot be separated into simpler substances by ordinary laboratory processes.
Dmitri Mendeleev
arranged the first 60 elements into groups.
There are how many elements identified?
118
Elements arranged in
the order of increasing atomic number.
Vertical columns are called
groups
Groups contain elements with
similar properties in vertical columns
Horizontal rows of elements
are periods
Groups are number from
1-18 or 1A-8A in earlier systems
Periods are numbered from
1-7
Period 1 has how many elements
2
Period 2&3 have how many elements
8
Period 4&5 have how many elements
18
Period 6 has how many elements
32
A group’s special name
main group/Representative elements
B Group’s special name
transition elements
Alkali Metals are in Group
1A
Alkali Metals properties
Soft, shiny metals
Good conductors of electricity and Heat
React vigorously with water
Form a white product when they react with oxygen
Hydrogen is not an alkali metal
Alkaline Earth Metals properties
Soft Shiny Metals
Conductors of Heat and Electricity
Reactive, but not as much as group 1 metals
Halogens properties
React with most elements
Noble gases
gases
nonreactive
Only a few compounds with other elements are known
Alkali Metals Group
1A or 1
Alkaline Earth Metals Group
2A or 2
Halogens Group
7A or 17
Noble Gas Group
8A or 18
Metals are located
on the left, except for hydrogen
Nonmetals are located
to the right
Metalloids are located
along the heavy zigzag line between the metals and nonmetals
Properties of metals
Metals are shiny solids except for mercury which is a liquid)
Malleable and ductile
They are good conductors of heat and electricity.
Melt at high temperatures
Have high densities
Properties of nonmetals
Nonmetals are dull brittle solids or gases at room temperatures.
Poor conductors
They are good insulators
Melt at low temperatures
Have low densities
Properties of Metalloids
Elements that have some properties similar metals and nonmetals
Are better conductors then nonmetals but not as good as metals
Are used as semiconductors and insulators
All elements are made up of
elements
All atoms of the same element are
identical
Atoms are
the smallest particle of an element that contain the characteristics of that element
Dalton’s Atomic theory-John Dalton
Every element is made up of tiny particles called atoms

All atoms of a given element are identical. They are different from atoms of other elements.

Atoms of two or more different elements combine in a definite proportion to form compounds.

A chemical reaction involves changes in the arrangement or combination of atoms. (Atoms are neither created or destroyed)

Electron Charge
Negative
Proton charge
Positive Charge
Protons and Neutrons are contained to
A small region called the nucleus
Neutrons charge
neutral
An atom consists
of a nucleus that contains protons and neutrons
Electrons are constantly moving in the large empty space around the nucleus
called the electron cloud
An atom of any element is electrically
neutral the net charge of an atom is zero
For a neutral atom
protons=electrons in numbers
The of which subatomic particle is negligible
electron
Where most of the mass in a atom
the nucleus
Chemist use atomic mass units
to give masses of atoms and subatomic particles
1amu=
1/12 the mass of a C-12 atom with 6 protons and 6 neutrons
Atomic Number is equal to the number
of protons in an atom
Atomic Number Appears
above the the symbol of an element in the periodic table different from the nuclear symbol
Mass Number
is the sum of the number of protons and number of neutrons in the nucleus.
Mass number=
number of protons+number of neutrons
Isotopes
are atoms of the same element that have different mass numbers.
They have the same number of protons but different number of neutrons
Nuclear Symbols
Helpful when specifying isotopes.
Gives the Mass number in the upper left hand corner and the atomic number in the lower left corner.
Atomic Mass is listed
below the symbol of each element on the periodic table
Atomic Mass gives the
average of the atom
Atom mass is
a weighted average of masses of all isotopes based on their fractional natural abundances
Electromagnetic Radiation
Is energy that travels as waves through space
Moves at the speed of light in a vacuum
Is described in terms of wavelength and frequency
Wavelength (lamda)
is the distance between the top of a wave to the top of the next wave

is expressed in meters (m)

Frequency (v,nu)
is the number of waves that pass by each second

Is expressed in cycles per second also uses hertz

Speed of light(c)=
frequency x wavelength
Electromagnetic Spectrum is
a collection of all forms of electromagnetic radiation
Visible light within
wavelengths 700-400nm
White light that passes through a prism
is separated into all colors called a continuous spectrum.

gives the colors of a rainbow

Atomic Spectrum
consists of lines of different colors (line spectrum)
What causes an atomic spectrum
formed when light from a heated element passes through a prism.
When an electron jumps to a higher energy level it
absorbs energy
An electron falls to a lower energy level by
emitting energy
Emitted radiation consists of small particles called
photons
The formula for the maximum number of electrons a energy level can hold
2n^2
the number of sublevels in an energy level is equal to
the principal quantum number (n)
Sub levels are designated with the letters
s p d f
Sublevels are also known as
subshells
maximum number of electrons in s
2
maximum number of electrons in p
6
maximum number of electrons in d
10
maximum number of electrons in f
14
S orbitals
has one orbital that holds 2 electrons
P orbitals
have 3 orbitals and can hold 6 electrons
d orbitals
have 5 orbitals and can hold 10 electrons
f orbitals
have 7 orbitals and can hold 14 electrons
Valence Electrons are
the electrons in the highest (outermost) energy level
Valence electrons in the electron configuration are the electrons in sublevels
s and p with the highest n number
All elements in the same group have
the same number of valence electrons
Number of valence electrons equal the
group number if using the the 1a-8a numbering system
Number of valence electrons equal
group number – 10 if you are using the 1-18 numbering system
Atomic radius is
the distance from the nucleus to the valence electrons
Atomic radius increases going down each group of Representative elements because
the number of energy levels increases
Atomic radius decreases going left to right across a period as
more protons increase nuclear attraction for valence electrons
Ionization energy is
the energy it takes to remove a valence electron
Metals have 1-3 valence electrons
lower ionization energy
Non metals have 5-7 valence electrons
higher ionization energy
Nobel Gases have complete octets (He has two valence electrons)
have the highest ionization energies in each period