Chapter 2 Reading Guide: Atoms and Elements
Name:____________________
The word atom comes from the Greek ___________, meaning “___________________.”
2.1 Imaging and Moving Individual Atoms (p. 45-47)
An atom is the smallest identifiable unit of ___________________________.
2.2 Early Ideas about the Building Blocks of Matter (p. 47)
The first people to propose that matter was composed of small, ______________________
particles were ____________________ and his student ________________________.
By the early 1800s certain observations led the English chemist ________________________ to
offer convincing evidence that supported the early atomic ideas of
_________________________ and ___________________________.
2.3 Modern Atomic Theory and the Laws That Led to It (p. 47-51)
Law of Conservation of Mass:
Law of Definite Proportions:
Law of Multiple Proportions:
John Dalton’s Atomic Theory:
1.
2.
3.
4.
2.4 The Discovery of the Electron (p. 51-53)
In the late 1800s an English physicist named ____________________ working at Cambridge
University, performed experiments to probe the properties of ____________________.
He found that the particles that compose the cathode ray have the following properties:
They travel in ________________ lines, they are ________________________ of the
composition of the material from which they originate, and they carry a
_________________________ electrical charge.
Attractive and repulsive forces are called _________________________ forces.
The area around a charged particle where these forces exist is called an
_______________________________________.
The value he measured implied that the cathode ray particle was about
_________________________ times ________________________ than hydrogen, the lightest
known atom.
_____________________________ had discovered the _________________________, a
______________________ charged, low mass particle present in _____________ atoms.
In 1909, American physicist _______________________________ performed his now famous
______________________________ experiment in which he deduced the ________________
of a single electron.
2.5 The Structure of the Atom (p. 54-56)
J.J. Thomson proposed that the negatively charged electrons were small particles held within a
_____________________________________ charged __________________.
This model became known as the ____________________________ model.
Alpha () particles are ________________ charged and the most _______________ of the three
types of radiation.
In 1909, Ernest Rutherford’s experiment, which employed _________ particles, proved
Thomson’s model __________________.
The _______________________ of the particles did pass directly through the gold foil, but some
particles were _____________________, and some even
____________________________________.
Rutherford realized the mass and positive charge of the atom must be
_______________________ in a space much ________________________ than the size of the
atom itself.
He proposed the ________________ theory of the atom, with three basic parts:
1.
2.
3.
British scientist ___________________________________ demonstrated that the previously
unaccounted for mass was due to ___________________________, ___________________
particles within the nucleus.
The dense nucleus contains over _______ % of the mass of the atom, but occupies
__________________________ of its volume.
An atom, like a cloud, is mostly _____________________________.
2.6 Subatomic Particles: Protons, Neutrons, and Electrons in Atoms (p. 56-61)
All atoms are composed of the same subatomic particles: ___________________,
___________________, and ____________________.
Protons and neutrons have nearly ___________________ masses.
Atomic mass unit (amu) is defined as ________________________________________________
_____________________________________________________________________________.
The mass of a proton or neutron is approximately _____ amu.
Electrons have an almost ____________ mass of __________________ amu.
The proton and electron both have _______________________.
In atomic units, the electron is assigned a charge of __________ and the proton is assigned a
charge of _________.
The charge of the proton and electron are ____________ in magnitude, but ________________
in sign.
The neutron has _________ charge.
Matter is usually _________________________ because protons and electrons are normally
present in _______________ numbers.
The number of _____________________ defines an element
The number of protons in an atom’s nucleus is its _______________________________ and is
given the symbol _________.
Each element is represented with a unique __________________________________, a one or
two letter abbreviation.
Atoms with the ___________ number of protons, but __________________ numbers of
neutrons are called __________________________.
Natural Abundance:
Mass Number:
Ions:
Cations:
Anions:
2.7 Finding Patterns: The Periodic Law and the Periodic Table (p. 61-66)
The modern periodic table grew out of the work of ___________________________.
Periodic Law:
Since many elements had not yet been discovered, Mendeleev’s table contained some
______________, which allowed him to predict the existence (and even the properties) of yet
___________________________________ elements.
For example, Mendeleev predicted the existence of an element he called
_______________________, which was later discovered and named
_______________________.
Metals:
Nonmetals:
Metalloids:
Semiconductors:
Main-group elements:
Transition elements or transition metals:
Family or group:
Noble Gases:
Alkali metals:
Alkaline earth metals:
Halogens:
A main group metal tends to __________ electrons, forming a ______________ with the same
number of ________________ as the nearest noble gas.
A main group nonmetal tends to ____________ electrons, forming an ____________ with the
same number of _______________ as the nearest noble gas.
2.8 Atomic Mass: The Average Mass of an Element’s Atoms (p. 66-70)
Atomic mass:
The atomic mass of each element represents the average mass of the _______________ that
compose that element, weighted according to the __________________________________ of
each isotope.
Mass Spectrometry:
The position of each peak on the x-axis indicates the ___________________________________
that was ionized and the intensity (indicated by the height of the peak) indicates the
________________________________________________________________.
2.9 Molar Mass: Counting Atoms by Weighing Them (p. 70-77)
Mole:
Avogadro’s number:
The value of the mole is equal to the number of ____________ in exactly
_________________________________________________________.
Molar Mass: