Chapter 2 Flashcards
the smallest identifiable unit of an element
atom
the matter that reacts
reactants
the matter that forms
product
The theory that all matter is composed of
atoms originated from several observations
and laws.
atomic theory
In a chemical reaction, matter is neither
created nor destroyed.
law of conservation of mass
law of conservation of mass
In a chemical reaction, matter is neither
created nor destroyed.
All samples of a given compound, regardless of
their source or how they were prepared, have the
same proportions of their constituent elements.
Law of definite proportions
When two elements (call them A and B) form
two different compounds, the mass of element
B that combine with 1 g of element A can be
expressed as a ratio of small whole numbers.
Law of multiple proportions
partially evacuated glass
tube called a
cathode ray tube
a beam of particles
cathode rays
negatively charged electrode
cathode
positively charged electrode
anode
a fundamental property of some of the particles that compose atoms and results in attractive and repulsive forces between hose particles
electrical charge
attractive and repulsive forces
electrostatic forces
the area around a charged particle
electric field
fundamental charge
–1.6 × 10–19
proposed that the negatively
charged electrons were small particles held
uniformlywithin a positively charged
sphere.
J.J. Thomson
directed
positively charged particles at an ultra thin
sheet of gold foil.
Ernest Rutherford
what did oil drop experiment do
deduce that the charge of a single electron
what did oil drop experiment do
deduce that the charge of a single electron Z
the emission of small energetic particles from the core of certain unstable atoms
radioactivity
a small core called a
nucleus
positively charged particles
protons
neutral particles within the nucleus
neutrons
the mass of a proton
1.67493 x 10 to the negative 27th power kg`
the mass of a neutron
1.67493 x 10 to the negative 27th power kg`
the mass of an electron
9.1 x 10 to the negative 31st power kg
unit to express the mass
atomic mass units (amu)
the most important number to identify an atom is
the number of protons
The number of protons in an atom’s nucleus is its
atomic number
what is the symbol fo 4th atomic number
Z
He
Helium
Helium
He
H
Hydrogen
Hydrogen
H
Li
Lithium
Lithium
Li
Be
Beryllium
Beryllium
Be
B
Boron
Boron
B
C
carbon
Carbon
C
N
Nitrogen
Nitrogen
N
O
Oxygen
Fluorine
F
Neon
Ne
Sodium
Na
Magnesium
Mg
Aluminum
Al
Silicon
Si
Phosphorus
P
Sulfer
S
Chlorine
Cl
Argon
Ar
potassium
K
Calcium
Ca
is either a one- or
two-letter abbreviation listed directly below
its atomic number on the periodic table.
chemical symbol
toms with the same number of protons
but a different number of neutrons are
called
isotopes
The relative amount of each isotope in a
naturally occurring sample of a given
element is roughly constant.
natural abundance
this has
allowed accurate measurements that reveal
small but significant variations in the natural
abundance of isotopes for many elements.
mass spectrometry
The sum of the number of neutrons and
protons in an atom is its
mass number
symbol for chemical symbol
X
Symbol for mass number
A
Atoms can lose or gain electrons and
become charged particles
ions
Atoms can lose or gain electrons and
become charged particles
ions
positively charges ions
cations
Negatively charged ions
anions
what is the law of periodic law
When the elements are arranged in order of
increasing atomic mass, certain sets of
properties recur periodically.
When the elements are arranged in order of
increasing atomic mass, certain sets of
properties recur periodically.
periodic law
Columns are
referred to as
groups
Rows are called
periods
predicted the existence
(and even the properties) of yet
undiscovered elements.
Mendeleev’s table
how are the elements listed in modern table
increasing in atomic number
where does metal reside on table
lower left side and middle
where do nonmetal lie
in the upper right side of the periodic table
how many nonmetals are there
17
where do metalloids lie
zigzag
diagonal line that divides metals and
nonmetals.
intermediate (and highly temperature-
dependent) electrical conductivity.
semiconductors
whose properties
tend to be largely predictablebased on their
position in the periodic table.
main-group elements
whose properties tend to be less predictable
based simply on their position in the
periodic table.
transition elements or transition metals
how Many groups are there
18
how many periods are there
7
the most unreacted elements
noble gases (8A)
the reactive metals
alkali metals (1A)
elements within a column are considered
families
They are fairly reactive
alkaline earth metals (2A)
are very reactive
nonmetals.
halogens (7A)
always found in nature as a salt
halogens
tend to lose electrons,
forming a cation with the same number of
electrons as the nearest noble gas.
main group metals
tend to gain electrons forming an anion with the same number of electrons as the nearest noble gas
main group nonmetals
elements in the same what have similar properties
group
have a tendency to lose one electron and
form 1+ ions.
alkali metals (group 1A)
tend
to lose two electrons and form 2+ ions.
alkaline earth metals (group 2A) `
tend to gain one
electron and form 1– ions.
halogens (group 7A)
tend to gain two electrons and form 2–
ions
oxygen family nonmetals (group 6A)
what are main-group elements that form
cations
metals
what are the main-group elements that form
anions (nonmetals) with predictable
charge equal to
the group number minus eight
average mass of the
isotopes that compose that element,
weighted according to the natural
abundance of each isotope.
atomic mass
where is the atomic mass shown
directly beneath the element’s symbol in
the periodic table.
a
technique that separates particles according
to their mass.
mass spectrometry
The masses of atoms and the percent abundances of isotopes of elements are measured using what
mass spectrometry
what does the position of each peak indicate
the mass of the isotopes
what dies the intensity (height of the peak) indicate
relative abundance of that isotope
where does chemical process happen?
between particles
is the amount (g)
per mole
molar mass
the amount of material containing 6.02214 x 10 to the 23rd particle
mole
the number of moles of a substance
the amount of a substance
the mass of one mole of an atom of an element is
molar mass
An element’s molar mass in grams per
mole is numerically equal what
atomic mass units (amu)
