HESI A2 Chemistry Latest Update 2024
Acid
a compound that is a hydrogen or proton donor. It is corrosive to metals, changes blue litmus paper
red, and becomes less acidic when mixed with bases
atom
the basic building block of a molecule that contains a nucleus and orbits
atomic mass
the average mass of each of that element's isotopes
atomic number
the number of protons in the nucleus, and it defines an atom of a particular element
base
a hydrogen or proton acceptor and generally has a hydroxide (OH) group in the makeup of the
molecule. Bases are also called alkaline compounds and are substances that denature proteins,
making them feel very slick; they change red litmus paper blue and become less basic when mixed
with acids.
basic unit of measure
standard unit of a system by which a quantity is accounted for and expressed (grams, liters, or
meters)
catalysts
substances that accelerate a reaction by reducing the activation energy or the amount of energy
necessary for a reaction to occur
Celsius
a temperature system used in most of the world and by the scientific community; It has these
characteristics:
zero degrees = freezing point of pure water at sea level
100 degrees = boiling point of pure water at sea level.
Most people have a body temperature of 37 degrees Celsius.
chemical equations
combination of elements or compounds called reactants responding to create a product or end result.
Equations are written in the following manner: reactants ---> products. The arrow can go the other
way or both ways
combustion
a self sustaining exothermic chemical reaction usually initiated by HEAT acting on OXYGEN and a fuel
compound such as hydrocarbons
compound
the combination of two or more elements or atoms
, covalent bond
2 atoms share electrons, generally in pairs, one from each atom
decomposition
a chemical reaction often described as the opposite of synthesis because it is the breaking of a
compound into its component parts
deoxyribose
a sugar used in the formation of DNA
double replacement
a reaction that involves two ionic compounds. The positive ion from one compound combines with
the negative ion of the other compound. The result is the two new ionic compounds that have
"switched partners"
electron clouds
the group of electrons revolving around the nucleus of an atom; a cloudlike group of electrons
equilibrium
a state in which reactants are forming products at the same rate that products are forming reactants
fahrenheit
a temperature measuring system used only in the US, its territories, Belize, and Jamaica. It is rarely
used for any scientific measurements except for body temperature.
It has these characteristics:
0 degrees is the freezing point of sea water or heavy brine at sea level;
32 degrees F is the freezing point of pure water at sea level;
212 degrees F is the boiling point of pure water at sea level; most people have a body temperature of
98.6 F
groups
elements that are placed together in columns in the periodic table
ionic bond
an electrostatic attraction between two oppositely charged ions or a cation and an anion. This type of
bond is generally formed between a METAL (cation) and a NON-METAL (anion)
isotope
different kinds of the same atom that vary in weight; for a given element, the number of
PROTONS=SAME, while the number of
neutrons = varies to make the different isotopes
kelvin
a unit of measure that is used only in the scientific community. Kelvin has these characteristics:
Acid
a compound that is a hydrogen or proton donor. It is corrosive to metals, changes blue litmus paper
red, and becomes less acidic when mixed with bases
atom
the basic building block of a molecule that contains a nucleus and orbits
atomic mass
the average mass of each of that element's isotopes
atomic number
the number of protons in the nucleus, and it defines an atom of a particular element
base
a hydrogen or proton acceptor and generally has a hydroxide (OH) group in the makeup of the
molecule. Bases are also called alkaline compounds and are substances that denature proteins,
making them feel very slick; they change red litmus paper blue and become less basic when mixed
with acids.
basic unit of measure
standard unit of a system by which a quantity is accounted for and expressed (grams, liters, or
meters)
catalysts
substances that accelerate a reaction by reducing the activation energy or the amount of energy
necessary for a reaction to occur
Celsius
a temperature system used in most of the world and by the scientific community; It has these
characteristics:
zero degrees = freezing point of pure water at sea level
100 degrees = boiling point of pure water at sea level.
Most people have a body temperature of 37 degrees Celsius.
chemical equations
combination of elements or compounds called reactants responding to create a product or end result.
Equations are written in the following manner: reactants ---> products. The arrow can go the other
way or both ways
combustion
a self sustaining exothermic chemical reaction usually initiated by HEAT acting on OXYGEN and a fuel
compound such as hydrocarbons
compound
the combination of two or more elements or atoms
, covalent bond
2 atoms share electrons, generally in pairs, one from each atom
decomposition
a chemical reaction often described as the opposite of synthesis because it is the breaking of a
compound into its component parts
deoxyribose
a sugar used in the formation of DNA
double replacement
a reaction that involves two ionic compounds. The positive ion from one compound combines with
the negative ion of the other compound. The result is the two new ionic compounds that have
"switched partners"
electron clouds
the group of electrons revolving around the nucleus of an atom; a cloudlike group of electrons
equilibrium
a state in which reactants are forming products at the same rate that products are forming reactants
fahrenheit
a temperature measuring system used only in the US, its territories, Belize, and Jamaica. It is rarely
used for any scientific measurements except for body temperature.
It has these characteristics:
0 degrees is the freezing point of sea water or heavy brine at sea level;
32 degrees F is the freezing point of pure water at sea level;
212 degrees F is the boiling point of pure water at sea level; most people have a body temperature of
98.6 F
groups
elements that are placed together in columns in the periodic table
ionic bond
an electrostatic attraction between two oppositely charged ions or a cation and an anion. This type of
bond is generally formed between a METAL (cation) and a NON-METAL (anion)
isotope
different kinds of the same atom that vary in weight; for a given element, the number of
PROTONS=SAME, while the number of
neutrons = varies to make the different isotopes
kelvin
a unit of measure that is used only in the scientific community. Kelvin has these characteristics:
