ACING EAPS 100 WITH ESSENTIAL A+ QUESTIONS AND
ANSWERS
What are the 3 fundamental sub-atomic particles which make up most atoms?
Protons (+ electrical charge) and neutrons (no electrical charge) reside in the center (nucleus)
an atom. Electrons (negatively charged), which are much smaller particles which whirl at great
speed around the nucleus, at different distances (orbitals). The outermost electrons can
transfer from one atom to another during chemical reactions.
How do you distinguish between the atomic number vs. the atomic weight of an element?
Atomic Number = # of protons (establishes the identity of an element)
Atomic Weight = # of protons & neutrons
What is an ion? How are they produced?
An ion is an electrically unbalanced atom. Normally, the number of electrons equal the number
of protons in an atom. If a single electron becomes dislodged, the atom acquires a charge of +1.
If an atom gains 2 extra electrons, the atom acquires a charge of -2.
What is an isotope? Are all isotopes radioactive?
An isotope is a natural-occurring variety of an element which contains extra neutrons this
changes the atomic weight, but does not change the atomic number, such as Carbon 14
("normal" carbon is Carbon 12), or deuterium ("heavy hydrogen"). Not all isotopes are
radioactive (such as Uranium 235); some are called stable isotopes, such as Oxygen 18
("normal" oxygen is Oxygen 16).
What is the most common element in the universe? In what form is this element found on
Earth?
Hydrogen is the most common element in the universe, about 70%. Because of its low density,
most of the original hydrogen in Earth's early atmosphere was lost to outer space, blown away
by the solar wind. Most of the hydrogen on earth is bound up as water, H2O.
,How did Earth originally form, and what relationship does it have with the Sun and the solar
system?
About 4.5 billion years ago, the Earth formed as one of the planets from left over cosmic dust
and gas from the formation of the Sun. The planets were spun into orbit by the whirling of the
cosmic dust cloud that later became the Sun. The Sun's gravity has kept the planets in orbit
ever since.
What are the terrestrial planets? What are the gas giants? What explains their different
origins within the same solar system?
The terrestrial (Earth-like) planets are relatively small and have rocky cores; they include
Mercury, Venus, Earth, and Mars; due to their proximity to the Sun, most of their original
hydrogen was blown away by the solar wind, early in the history of the solar system. The gas
giants are much larger planets which retained much of their original hydrogen due to their
great distance from the sun, and include Jupiter, Saturn, Neptune, and Uranus. (Pluto seems to
resemble a terrestrial planet, and is believed to be a moon captured by Neptune's gravity.)
How old is the Earth, and how do we know this?
Although the oldest rocks found on Earth are about 3.8 billion years old, the age of the Earth is
set at about 4.5 billion years, using radiometric dating to determine the age of meteorites
found on Earth. Meteorites are left over material from the formation of the solar system it is
assumed that Earth was formed at the same time as the meteorites from common origins.
What are the sources of the earth's internal heat?
Earth's internal heat has several sources, accumulated from its earliest history:
heat of accretion (collisions of cosmic dust, meteorites, asteroids, and comets during Earth's
earliest history
heat from radioactive decay of elements in the earth's interior
Heat always flows from a hotter place to a cooler place; therefore, the earth's internal heat has
been trying to escape ever since the planet formed. This internal heat drives processes such as
, the movement of the tectonic plates, the formation of magma, volcanism, mountain building,
and earthquakes.
What is the source of the earth's external heat?
The sun is the source of the earth's external heat, which drives the earth's weather patterns,
which in turn affect the surface processes of weathering and erosion.
Explain how the earth's processes are in a dynamic equilibrium .
Over geologic time, the earth's internal processes which create new rock (volcanism, mountain-
building) are balanced against earth's surface processes which destroy rock (weathering,
erosion), as evidenced by the diversity of landscapes that exists. An erosion-dominated Earth
would eventually become completely covered by the oceans, while a mountain-building
dominated Earth would eventually become completely mountainous with no flat-lying plains.
What is the most common element in the earth's crust? What are the 8 most common
elements in the earth's crust? What is the most common element in the earth's interior?
Oxygen is the most common element in the earth's crust. The 8 most common elements (from
most to least abudant) in the earth's crust are: O, Si, Al, Fe, Ca, Na, K, and Mg (oxygen, silicon,
aluminum, iron, calcium, sodium, potassium, magnesium). This list does NOT apply to earth as a
whole, because the most common element in the earth's interior is iron, which makes up the
inner and outer core.
What is a chemical compound? How can compounds differ from their constituent elements?
Any combination of 2 or more elements is a compound. Many compounds differ drastically
from their constituent elements; for example, sodium chloride is an edible compound, but
sodium is a toxic, flammable metal, while chlorine is a poisonous gas.
What is a crystalline substance? In contrast, what is a glass, or an amorphous solid?
A crystalline substance is an ordered solid, whose atoms are arranged in an orderly, repeating
internal arrangement; a unit of such as substance is called a crystal. A glass is an unordered
ANSWERS
What are the 3 fundamental sub-atomic particles which make up most atoms?
Protons (+ electrical charge) and neutrons (no electrical charge) reside in the center (nucleus)
an atom. Electrons (negatively charged), which are much smaller particles which whirl at great
speed around the nucleus, at different distances (orbitals). The outermost electrons can
transfer from one atom to another during chemical reactions.
How do you distinguish between the atomic number vs. the atomic weight of an element?
Atomic Number = # of protons (establishes the identity of an element)
Atomic Weight = # of protons & neutrons
What is an ion? How are they produced?
An ion is an electrically unbalanced atom. Normally, the number of electrons equal the number
of protons in an atom. If a single electron becomes dislodged, the atom acquires a charge of +1.
If an atom gains 2 extra electrons, the atom acquires a charge of -2.
What is an isotope? Are all isotopes radioactive?
An isotope is a natural-occurring variety of an element which contains extra neutrons this
changes the atomic weight, but does not change the atomic number, such as Carbon 14
("normal" carbon is Carbon 12), or deuterium ("heavy hydrogen"). Not all isotopes are
radioactive (such as Uranium 235); some are called stable isotopes, such as Oxygen 18
("normal" oxygen is Oxygen 16).
What is the most common element in the universe? In what form is this element found on
Earth?
Hydrogen is the most common element in the universe, about 70%. Because of its low density,
most of the original hydrogen in Earth's early atmosphere was lost to outer space, blown away
by the solar wind. Most of the hydrogen on earth is bound up as water, H2O.
,How did Earth originally form, and what relationship does it have with the Sun and the solar
system?
About 4.5 billion years ago, the Earth formed as one of the planets from left over cosmic dust
and gas from the formation of the Sun. The planets were spun into orbit by the whirling of the
cosmic dust cloud that later became the Sun. The Sun's gravity has kept the planets in orbit
ever since.
What are the terrestrial planets? What are the gas giants? What explains their different
origins within the same solar system?
The terrestrial (Earth-like) planets are relatively small and have rocky cores; they include
Mercury, Venus, Earth, and Mars; due to their proximity to the Sun, most of their original
hydrogen was blown away by the solar wind, early in the history of the solar system. The gas
giants are much larger planets which retained much of their original hydrogen due to their
great distance from the sun, and include Jupiter, Saturn, Neptune, and Uranus. (Pluto seems to
resemble a terrestrial planet, and is believed to be a moon captured by Neptune's gravity.)
How old is the Earth, and how do we know this?
Although the oldest rocks found on Earth are about 3.8 billion years old, the age of the Earth is
set at about 4.5 billion years, using radiometric dating to determine the age of meteorites
found on Earth. Meteorites are left over material from the formation of the solar system it is
assumed that Earth was formed at the same time as the meteorites from common origins.
What are the sources of the earth's internal heat?
Earth's internal heat has several sources, accumulated from its earliest history:
heat of accretion (collisions of cosmic dust, meteorites, asteroids, and comets during Earth's
earliest history
heat from radioactive decay of elements in the earth's interior
Heat always flows from a hotter place to a cooler place; therefore, the earth's internal heat has
been trying to escape ever since the planet formed. This internal heat drives processes such as
, the movement of the tectonic plates, the formation of magma, volcanism, mountain building,
and earthquakes.
What is the source of the earth's external heat?
The sun is the source of the earth's external heat, which drives the earth's weather patterns,
which in turn affect the surface processes of weathering and erosion.
Explain how the earth's processes are in a dynamic equilibrium .
Over geologic time, the earth's internal processes which create new rock (volcanism, mountain-
building) are balanced against earth's surface processes which destroy rock (weathering,
erosion), as evidenced by the diversity of landscapes that exists. An erosion-dominated Earth
would eventually become completely covered by the oceans, while a mountain-building
dominated Earth would eventually become completely mountainous with no flat-lying plains.
What is the most common element in the earth's crust? What are the 8 most common
elements in the earth's crust? What is the most common element in the earth's interior?
Oxygen is the most common element in the earth's crust. The 8 most common elements (from
most to least abudant) in the earth's crust are: O, Si, Al, Fe, Ca, Na, K, and Mg (oxygen, silicon,
aluminum, iron, calcium, sodium, potassium, magnesium). This list does NOT apply to earth as a
whole, because the most common element in the earth's interior is iron, which makes up the
inner and outer core.
What is a chemical compound? How can compounds differ from their constituent elements?
Any combination of 2 or more elements is a compound. Many compounds differ drastically
from their constituent elements; for example, sodium chloride is an edible compound, but
sodium is a toxic, flammable metal, while chlorine is a poisonous gas.
What is a crystalline substance? In contrast, what is a glass, or an amorphous solid?
A crystalline substance is an ordered solid, whose atoms are arranged in an orderly, repeating
internal arrangement; a unit of such as substance is called a crystal. A glass is an unordered
