Download Ch 17 Notes

Name________________________________Block_______Date__________________
Ch 17 Atomic Nature of Matter Notes Mrs. Peck
atoms- the smallest particle of an element that can be identified with that element
are the building blocks of matter
consists of protons and neutrons in a nucleus surrounded by electrons
element-a substance made of only one kind of atom
atoms of the same kind make up an element
atoms w/ same # of protons belong to same element
atoms w/ diff. # of protons are different elements
115 elements known today
90 elements occur in nature,
rest made in laboratory with high-energy accelerators and nuclear reactors
[ these are too unstable (radioactive) to occur naturally ]
99% of material on Earth is formed from only about a dozen elements
Living things: composed primarily of 6 elements CHNOPS
carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), sulfur (S)
organism-cells-molecules & compounds-atoms-
1)nucleons: protons & neutrons
2)electrons
hydrogen- the lightest of all elements
most abundant element in universe (90% of all atoms are H)
helium- second lightest element
makes up most of the remaining atoms in universe
rare on Earth
TABLE 17.1 pg 245
most common elements and their symbols
Element is represented by a symbol.
mass #
consists of 1 or 2 letters.
1st- capitalized
charge
Symbol
2nd- lower case
atomic #
eg.
atoms are recyclable: they cycle & recycle among numerous forms: both living & nonliving
Atoms are very small
smaller than wavelength of visible light, so can not see them with a compound light microscope
Atoms are constantly moving..........add heat.....adds E....atoms move faster....∆ phase
solid: low rate of movement
liquid: more movement
gas: highest rate of movement
2
molecule or compound two or more atoms of the same or different elements bonded to form a
larger particle
matter that is a gas or liquid at room temperature is usually made of molecules
there is a limited number of different atoms, but there are many different molecules
molecules & compounds have different properties from the elements which they are made
eg: oxygen or nitrogen gas
methane gas CH4
O2
N2
water H2O is a molecule
table salt (sodium chloride) NaCl is a compound
Chemical formula- a description that uses numbers and symbols of elements to describe the
proportions of elements in a compound or reaction.
represented using element symbols
a subscript number directly after the symbol indicates the # of atoms of that element
If there is only one atom of an element then the number 1 is omitted and understood
ex. H2S O4
sulfuric acid consists of 2 hydrogen atoms, 1 sulfur atom, 4 oxygen atoms
Na3PO3
sodium phosphate has 3 sodium atoms, 1 phosphorus atom, 3 oxygen atoms
C 6H12O 6
glucose has 6 atoms of carbon, 12 atoms of hydrogen, 6 atoms of oxygen
CaCl
calcium chloride has 1 atom of calcium and 1 atom of chloride
3
atom- has a nucleus in the center (protons& neutrons) w/ electrons orbiting around nucleus
nucleus-the positively charged center of an atom
contains nucleons: protons and neutrons
has almost all the mass of the entire atom but only a tiny fraction of the volume
the center mass filled region of an atom
very compact and dense, nucleus small compared to the actual size of the atom
nucleons- the principal building block of the nucleus: proton and neutron
neutron- an electrically neutral particle that is one of the two kinds of particles that
compose an atomic nucleus
all neutrons are identical
proton- a positively charged particle that is one of the two kinds of particles found
in the nucleus of an atom
all protons are identical
atoms of different elements differ from one another by their _________________
atoms with the same number of protons all belong to the same_______________
if an atom has a different # of protons then________________________________
Atomic number- number of protons in the nucleus of an atom
elements are organized in the periodic table by their atomic number
eg. hydrogen- has 1 proton ....atomic number is 1
helium- has 2 protons........atomic number is 2
lithium- has 3 protons.........atomic number is 3
PEA- # protons = # electrons = atomic number
(atoms with no charge except for ions)
Atomic mass number- total number of nucleons (neutrons & protons) in the nucleus of an atom
4
atom- has a nucleus in the center (protons and neutrons) with electrons orbiting around nucleus at
different levels (shells)
electrons are negatively charged particles that orbit around the nucleus
electrons are very small& do not significantly contribute to the atomic mass of atom
mass of electron is small compared to mass of a nucleon
in a electrically neutral atom: the number of electrons equals the number of protons
shell model of the atom- a model in which the electrons of an atom are grouped in concentric
shells around the nucleus
electrons are believed to be orbiting in spherical shells around the nucleus (it is actually more complicated
there are 7 shells 1st can hold up to 2 e2nd can hold up to 8 e3rd can hold up to 18 e-
electron configuration / arrangement of electrons
*it is the electrons in the outer shell that dictate the bonding properties and chemical
properties of an element such as melting point, taste, color, ect.
determines how element with react or bond with other elements or atoms
for a given element: the number of protons never changes
5
the number of protons equals number of electrons (neutral atom)
the number of neutrons will vary........mass will vary.....isotope
isotope- a form of an element having a particular number of neutrons in the nuclei of its atoms.
Different isotopes of the same element have 1. same atomic number (same # protons)
2. different atomic mass numbers
(mass = # protons + # neutrons)
isotope: atoms of the same element having same number of protons and different
numbers of neutrons.....varying the atomic mass
every element has a variety of isotopes
eg. carbon 12C
14C
has 6 protons and 6 neutrons....mass number=12
has 6 protons and 8 neutrons....mass number =14
6
ion- atom or group of atoms with a net electric charge, due to the loss or gain of electrons
when the number of electrons is more or less than the number of protons in an atom
ion has a net charge:
positive if the number of electrons is less than the number of protons
eg. Na+ , K+ , Ca+2 these atoms have 1 or 2 more protons than enegative if the number of electrons is more than the number of protons
eg. Cl-, Br - these atoms have 1 more e- than protons
Bonding:
attraction between a proton and an electron can cause a bond between atoms to form a molecule
electrons can be transferred between two atoms to form a bond between 2 atoms
2 types of bonding:
1. ionic bonding- one atom gives up electron(s) and one atom gains electron(s
2. covalent bonding-electrons are shared between two atoms
7
Neutral atom
19
element
fluorine
symbol
F
9
9P
10 N
Atomic #
protons
mass #
nucleons
neutrons
electrons
charge 0
9
9
19
19
10
9
Isotope
14
element
carbon
symbol
C
6
6P
8N
Atomic # 6
protons
6
mass # 12
nucleons 14
neutrons
8
electrons 6
charge
0
isotope 14C
Ion
35
element
17 P
18N
chlorine
Atomic # 17
protons
17
mass #
35
nucleons 35
neutrons 18
electrons 19
charge
-1
isotope
no
symbol
-1
Cl
17
periodic table- a chart that lists elements by atomic number and by electron arrangements,
so that elements with similar chemical properties are in the same column
8
from left to right: each element has one more proton & electron than the preceding element
elements that are “side by side”
the atomic # increases from left to right and from top to bottom
the atomic mass generally increases from left to right and from top to bottom
metals: elements to the left of the heavy line running stepwise from boron to astatine
malleable, conduct electricity & heat
nonmetals:elements to the right of the heavy line running stepwise from boron to astatine
non conductors, at room temp- gas or liquid, non-reflective
period- elements in the same row in periodic table, they have same number electron shells as
period number
eg. period 1: is 1st row, elements have electrons only in 1st shell
period 2: is 2nd row, elements all have electrons in 1st and 2nd shell only
as you go down a column, each element has one more shell filled to its capacity
in each period, as the atomic number increases in the period, the elements generally
change from very active metals, to less active metals, to metalloids, to less active
nonmetals, to very active nonmetals
Group-elements in the same column in periodic table, they have similar chemical properties and
react with other elements in the same way to form new compounds because their
outermost electrons are arranged the same way
group 1
group 2
group 3-12
group 7
group 8
alkali metals
alkaline earths
transitional metals
other metals
metalloids
non-metals
halogens
noble gases
elements tend to form ions by borrowing or lending electrons to produce the electron
configuration-arrangement of the nobel gas closest in atomic number
this is the “magic rule of 8” (or 2)
Phases of Matter
in all phases of matter the atoms are constantly in motion
9
Atoms are constantly moving..........add heat.....adds energy....atoms move faster....change phase
solid: low rate of movement
liquid: more movement
gas: highest rate of movement
4 phases: solid: atoms and molecules vibrate about a fixed position
liquid: increased molecular motion, the molecules move in non fixed position & take
on the shape of its container
molecules flow freely from postion to position sliding over one another.
is a fluid- anything that flows
take on shape of its container
gas: increased energy causes molecules to move about at higher rates & break
away from each other
molecules are far away from each other, enabling continuous movement,
they will periodically have elastic collisions with not net change in Energy
is a fluid- anything that flows
take on shape of its container
primary difference b/w liquid and gas: is the distance b/w molecules due
to the E that the molecules have.
plasma: exists mainly at extremely high temperatures (2000 C°) matter consists
of positively charged ions and free electrons
matter consists of positive ions (atoms that are missing some electrons)
and free electrons
predominant phase of matter in the universe such as in stars