HESI A2 CHEmIStry (2025/2026): UpdAtEd EdItIon
FEAtUrIng VErIFIEd QUEStIonS And rElIAblE, In-
dEptH AnSwErS From trUStEd SoUrCES
1. What makes an atom's physical structure? - ANSWER A nucleus and
orbits(sometimes known as electron clouds)
2. What composes the center of the atom? - ANSWER Protons and neutrons
3. What spins in the orbits of an atom? - ANSWER Electrons
4. What are the energy levels of the atom called? - ANSWER Shells or orbits
5. What is the term used to define an atom that is electrically charged? -
ANSWER Ionic state.
6. What is a cation? - ANSWER An atom with a positive charge
7. What is anion? - ANSWER An atom with a negative charge
8. What is the structure of the periodic table? - ANSWER A series of rows
called periods, and columns called groups.
9. What can be predicted by the group an element occupies? - ANSWER
Charge and the numbers of electrons in its outer shell.
,10.What is the name and properties of group VIII of the periodic table? -
ANSWER Noble gases.
11.They tend to remain neutral in most situations, because their outer orbits are
complete.
12.What is the atomic number? - ANSWER The number of protons in the
nucleus, defines an atom of a particular element.
13.What is the atomic mass? - ANSWER The average mass of an element's
isotopes.
14.What are isotopes? - ANSWER Different kinds of the same atom that vary in
weight.
15.What is a compound? - ANSWER The combination of different elements.
16.What do chemical reactions resemble? - ANSWER A cooking recipe.
17.What are the reactants in a chemical reaction? - ANSWER The ingredients
of a chemical reaction.
18.What is the term given to the results of a chemical reaction? - ANSWER The
products.
,Why must a chemical equation be balanced at the end of a reaction? - ANSWER
Because the law of conservation of mass indicates that mass cannot be created nor
destroyed in a chemical reaction.
kelvin (K) - ANSWER used only in the scientific community
-zero degrees (0K): equals -273.15 degrees celsius and *is thought to be the lowest
temperature achievable or absolute zero (0)*
-273K: *freezing point of water*
-373K: *boiling point of water*
-310K: *normal body temp of temp for a person, but this is never used*
atom - ANSWER the basic building block of all molecules
nucleus - ANSWER the center of an atom and is composed of protons and
neutrons
electrons - ANSWER negatively charged
spin around the nucleus at various energy levels at fantastic speeds, forming
electron clouds
protons - ANSWER positively charged
neutron - ANSWER no charge at all
ground state atoms - ANSWER equal numbers of protons and electrons, making
them electrically neutral
, ion - ANSWER -when an atom is electrically charged; in an ionic state
-occurs when it is in a solution or in the form of a chemical compound
cation - ANSWER -positive charge
an atom in an ionic state will have lost in electrons, resulting in a net positive
charge
anion - ANSWER -negative charge
an atom in an ionic state that will have gained electrons, resulting in a net negative
charge
periodic table - ANSWER a table of the known elements arranged according to
their properties; makes it possible to predict the properties of each element based
on its location on the table
-made up of a series of rows called *periods* and columns called *groups*
atomic number - ANSWER the number of protons in the nucleus, and it defines an
atom as a particular element
(atomic number = number of protons)
atomic mass - ANSWER the average mass of each of that elements isotopes
(protons+neutrons)
isotopes - ANSWER different kinds of the same atom that vary in weight, which
comes about when the number of protons in an element stay the same while the
number of neutrons varies
FEAtUrIng VErIFIEd QUEStIonS And rElIAblE, In-
dEptH AnSwErS From trUStEd SoUrCES
1. What makes an atom's physical structure? - ANSWER A nucleus and
orbits(sometimes known as electron clouds)
2. What composes the center of the atom? - ANSWER Protons and neutrons
3. What spins in the orbits of an atom? - ANSWER Electrons
4. What are the energy levels of the atom called? - ANSWER Shells or orbits
5. What is the term used to define an atom that is electrically charged? -
ANSWER Ionic state.
6. What is a cation? - ANSWER An atom with a positive charge
7. What is anion? - ANSWER An atom with a negative charge
8. What is the structure of the periodic table? - ANSWER A series of rows
called periods, and columns called groups.
9. What can be predicted by the group an element occupies? - ANSWER
Charge and the numbers of electrons in its outer shell.
,10.What is the name and properties of group VIII of the periodic table? -
ANSWER Noble gases.
11.They tend to remain neutral in most situations, because their outer orbits are
complete.
12.What is the atomic number? - ANSWER The number of protons in the
nucleus, defines an atom of a particular element.
13.What is the atomic mass? - ANSWER The average mass of an element's
isotopes.
14.What are isotopes? - ANSWER Different kinds of the same atom that vary in
weight.
15.What is a compound? - ANSWER The combination of different elements.
16.What do chemical reactions resemble? - ANSWER A cooking recipe.
17.What are the reactants in a chemical reaction? - ANSWER The ingredients
of a chemical reaction.
18.What is the term given to the results of a chemical reaction? - ANSWER The
products.
,Why must a chemical equation be balanced at the end of a reaction? - ANSWER
Because the law of conservation of mass indicates that mass cannot be created nor
destroyed in a chemical reaction.
kelvin (K) - ANSWER used only in the scientific community
-zero degrees (0K): equals -273.15 degrees celsius and *is thought to be the lowest
temperature achievable or absolute zero (0)*
-273K: *freezing point of water*
-373K: *boiling point of water*
-310K: *normal body temp of temp for a person, but this is never used*
atom - ANSWER the basic building block of all molecules
nucleus - ANSWER the center of an atom and is composed of protons and
neutrons
electrons - ANSWER negatively charged
spin around the nucleus at various energy levels at fantastic speeds, forming
electron clouds
protons - ANSWER positively charged
neutron - ANSWER no charge at all
ground state atoms - ANSWER equal numbers of protons and electrons, making
them electrically neutral
, ion - ANSWER -when an atom is electrically charged; in an ionic state
-occurs when it is in a solution or in the form of a chemical compound
cation - ANSWER -positive charge
an atom in an ionic state will have lost in electrons, resulting in a net positive
charge
anion - ANSWER -negative charge
an atom in an ionic state that will have gained electrons, resulting in a net negative
charge
periodic table - ANSWER a table of the known elements arranged according to
their properties; makes it possible to predict the properties of each element based
on its location on the table
-made up of a series of rows called *periods* and columns called *groups*
atomic number - ANSWER the number of protons in the nucleus, and it defines an
atom as a particular element
(atomic number = number of protons)
atomic mass - ANSWER the average mass of each of that elements isotopes
(protons+neutrons)
isotopes - ANSWER different kinds of the same atom that vary in weight, which
comes about when the number of protons in an element stay the same while the
number of neutrons varies
