TEXES 7-12 CHEMISTRY EXAM 2025
QUESTIONS AND ANSWERS
alpha decay - ANSWER-nucleus emits an alpha particle with 2 protons and 2
neutrons, leaving the rest of the nucleus behind. atomic number of the isotope
decreases by 2 and the mass by 4. energy carried away in the form of kinetic
beta decay - ANSWER-a neutron changes into a proton by emitting an electron
and a neutrino from the nucleus. the atomic # of the isotope increases by 1 but the
mass stays the same.
gamma decay - ANSWER-electromagnetic energy is released from the nucleus in
the form of a gamma ray. atomic # and mass do not change
half life - ANSWER-initial amount (.5)^(time elapsed/half life)
Carbon dating - ANSWER-half-lives to determine the approximate age of fossils
under 70,000 years . Carbon-14 which is an unstable isotope of carbon has a half-
life of about 5,000 years.
density - ANSWER-the amount of mass present in a given volume. Reflection of
how tightly packed the atoms are.
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,water density - ANSWER-Water has a density of 1 gram per cubic centimeter.
hardness - ANSWER-the mineral's resistance to scratching; measured on the Mohs
scale, where talc, the softest mineral, has a score of 1 and diamond, the hardest, has
a score of 10
diamond is hard, talc is soft
radioactivity - ANSWER-When an atom changes the number of protons in the
nucleus and releases radiation; used in medicine
alpha particles - ANSWER-the least dangerous to humans when exposed externally
because of its low penetrating power
xray - ANSWER-high-energy rays that can penetrate the skin and organs and can
be used for medical imaging.
radiometric dating - ANSWER-The age of very old igneous rocks can be
determined; half-lives of the parent isotopes in the rock, ratio of the amounts of
parent and daughter isotopes in the rock
John Dalton - ANSWER-spherical atom
JJ Thompson - ANSWER-plum pudding theory; atom is spherical, but proton,
neutrons and electrons were floating like fruits
Rutherford - ANSWER-identified nucleus; positive particles concentrated in the
center of an atom
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, Bohr - ANSWER-fixed rutherford; added electron rings (planetary model)
Schrodinger - ANSWER-Quantum Model; electrons move in waves around the
nucleus rather than fixed orbitals
transition metals - ANSWER-solid at room temp, conductors shiny malleable
bond order - ANSWER-bonding electrons-antibonding electrons/2
Ionization energy - ANSWER-how much energy is required to make an atom into
an ion by losing an electron. It increases from left to right across the periodic table
and increases bottom to top.
Electron affinity - ANSWER-the ability to accept an electron and become a more
negative ion
Fluorine (group 17) has a higher electron affinity than Oxygen (group 16) ; It
increases from left to right and bottom to top, with the exception of the noble
gases because they will not accept an electron.
Atomic radius - ANSWER-distance from the nucleus to the outer electron shell. It
decreases left to right across the periodic table because the nucleus increases in size
which increases the electrostatic pull on the electrons towards the nucleus.
However, it increases top to bottom as the atoms gain a new electron shell.
Metallic qualities - ANSWER-things such as magnetism, conductivity, malleability,
and ductility. There are different types of magnetism and it varies among elements.
Conductivity, malleability, and ductility also vary within metals.
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QUESTIONS AND ANSWERS
alpha decay - ANSWER-nucleus emits an alpha particle with 2 protons and 2
neutrons, leaving the rest of the nucleus behind. atomic number of the isotope
decreases by 2 and the mass by 4. energy carried away in the form of kinetic
beta decay - ANSWER-a neutron changes into a proton by emitting an electron
and a neutrino from the nucleus. the atomic # of the isotope increases by 1 but the
mass stays the same.
gamma decay - ANSWER-electromagnetic energy is released from the nucleus in
the form of a gamma ray. atomic # and mass do not change
half life - ANSWER-initial amount (.5)^(time elapsed/half life)
Carbon dating - ANSWER-half-lives to determine the approximate age of fossils
under 70,000 years . Carbon-14 which is an unstable isotope of carbon has a half-
life of about 5,000 years.
density - ANSWER-the amount of mass present in a given volume. Reflection of
how tightly packed the atoms are.
COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,water density - ANSWER-Water has a density of 1 gram per cubic centimeter.
hardness - ANSWER-the mineral's resistance to scratching; measured on the Mohs
scale, where talc, the softest mineral, has a score of 1 and diamond, the hardest, has
a score of 10
diamond is hard, talc is soft
radioactivity - ANSWER-When an atom changes the number of protons in the
nucleus and releases radiation; used in medicine
alpha particles - ANSWER-the least dangerous to humans when exposed externally
because of its low penetrating power
xray - ANSWER-high-energy rays that can penetrate the skin and organs and can
be used for medical imaging.
radiometric dating - ANSWER-The age of very old igneous rocks can be
determined; half-lives of the parent isotopes in the rock, ratio of the amounts of
parent and daughter isotopes in the rock
John Dalton - ANSWER-spherical atom
JJ Thompson - ANSWER-plum pudding theory; atom is spherical, but proton,
neutrons and electrons were floating like fruits
Rutherford - ANSWER-identified nucleus; positive particles concentrated in the
center of an atom
COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
, Bohr - ANSWER-fixed rutherford; added electron rings (planetary model)
Schrodinger - ANSWER-Quantum Model; electrons move in waves around the
nucleus rather than fixed orbitals
transition metals - ANSWER-solid at room temp, conductors shiny malleable
bond order - ANSWER-bonding electrons-antibonding electrons/2
Ionization energy - ANSWER-how much energy is required to make an atom into
an ion by losing an electron. It increases from left to right across the periodic table
and increases bottom to top.
Electron affinity - ANSWER-the ability to accept an electron and become a more
negative ion
Fluorine (group 17) has a higher electron affinity than Oxygen (group 16) ; It
increases from left to right and bottom to top, with the exception of the noble
gases because they will not accept an electron.
Atomic radius - ANSWER-distance from the nucleus to the outer electron shell. It
decreases left to right across the periodic table because the nucleus increases in size
which increases the electrostatic pull on the electrons towards the nucleus.
However, it increases top to bottom as the atoms gain a new electron shell.
Metallic qualities - ANSWER-things such as magnetism, conductivity, malleability,
and ductility. There are different types of magnetism and it varies among elements.
Conductivity, malleability, and ductility also vary within metals.
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