Download 1 Chapter 4 Atomic Structure 4.1 Defining the Atom Early Models of

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Chapter 4 Atomic Structure
4.1 Defining the Atom
Early Models of the Atom
An _____________ is the smallest particle of an element that retains it identity in
a chemical reaction.
The Greek philosopher Democritus (460 B.C. - 370 B.C) was among the first to
suggest the existence of atoms. Democritus believed that atoms were indivisible
and _______________________.
Dalton's Atomic Theory
The modern process of discovery regarding atoms began with John
_____________ (1766-1844).
By using experimental methods. Dalton transformed Democritus's ideas on atoms
into a scientific theory.
Dalton's atomic theory
1. All elements are composed of tiny indivisible particles called ______________.
2. Atoms of the same element are identical. The _____________ of any one
element are different from those of any other element.
3. Atoms of different elements can physically mix together or can chemically
combine in simple whole-number ratios to form compounds.
4. Chemical reactions occur when _____________ are separated, joined or
rearranged. Atoms of one element, however are never changed into atoms or
another element as a result of a chemical reaction.
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Sizing up the Atom
Copper atoms are very small. A pure copper coin the size of a penny contains
about 2.4 x 1022 _______________.
By comparison, Earth's population is only about 6 x 109 people.
If you could line up _____________________ copper atoms side by side, they
would produce a line only 1 cm long!
The radii of most atoms fall within the range of 5 x10-11 m to 2 x 10-10 m.
4.2 Structure of the Nuclear Atom
Subatomic Particles
Three kinds of subatomic particles are electrons, ________________, and
neutrons.
In 1897, the English physicist J. J. Thomson (1856-1940) discovered the electron.
__________________ are negatively charged subatomic particles.
In a ____________________ tube, electrons travel as a ray from the cathode (-)
to the anode (+).
Such positively charged subatomic particles are called ________________. Each
proton has a mass about 1840 times that of an electron.
_________________ are subatomic particles with no charge but with a mass
nearly equal to that of a proton.
Although protons and neutrons are exceedingly small, theoretical physicists
believe that they are composed of yet smaller subnuclear particles called
___________________.
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The Atomic Nucleus
The _________________ is the tiny central core of an atom and is composed of
protons and neutrons.
Rutherford's gold-foil experiment yielded evidence of the atomic nucleus.
In the nuclear atom, the ______________and neutrons are located in the nucleus.
The electrons are distributed around the nucleus and occupy almost all the
volume of the ________________.
4.3 Distinguishing Among Atoms
Atomic Number
Atoms are composed of _____________, neutron, and electrons.
_______________ and neutrons make up the nucleus.
Elements are different because they contain different numbers of
__________________.
The _______________ number of an element is the number of protons in the
nucleus of an atom of that element.
Mass Number
The total number of protons and neutrons in an atom is called the
_____________ number.
The number of neutrons in an atom is the difference between the mass number
and atomic number.
Isotopes
______________ are atoms that have the same number of protons but different
numbers of ________________, they also have different mass numbers.
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Atomic Mass
An atomic ____________ unit (amu) is defined as one twelfth of the mass of a
carbon-12 atom.
The ______________ mass of an element is a weighted average mass of the
atoms in a naturally occurring sample of the element.
To calculate the atomic mass of an ______________, multiply the mass of each
isotope by its natural abundance, expressed as a decimal, and then add the
products.
The Periodic Table---A preview
A _____________table is an arrangement of elements in which the elements are
separated into groups based on a set of repeating properties.
Each horizontal row of the periodic table is called a _______________. There are
____________ periods in the modern periodic table.
Each vertical column of the periodic table is called a ___________, or family.
Elements within a group have similar chemical and physical properties.