HESI A2 Chemistry Latest Update 2024
Chemistry
The study of matter and its properties and how those properties relate to one another
Three states of matter
solid, liquid, gas
Scientific notation
The scientific system of writing numbers. A method to write very big or very small numbers easily. Is
composed of three parts: a mathematical sign, + or -, the significand, and the exponential, sometimes
called the logarithm.
Mathematical sign
designates whether the number is positive or negative
(+ or -)
Significand
the base value of the number or the value of the number when all the values of ten are removed
Exponential
A multiplier of the significand in powers of ten. Move the decimal in the significand the number of
places equal to the exponent of 10. positive to the right, negative to the left. Numbers between -1
and 1 always place a zero to the left of the decimal.
Temperature systems
Fahrenheit, Celsius, and Kelvin
Fahrenheit (F)
Used only in US, Belize, and Jamaica. 0 degrees is the freezing point of sea water or heavy brine at sea
level. 32 degrees is the freezing point of pure water at sea level, 212 degrees is the boiling point of
pure water at sea level. most people body temp s 98.6 degrees
Celsius (C)
sometimes called Centigrade and is used in the rest of the world and by the scientific community. 0
degree is the freezing point of pure water at sea level, 100 degrees is the boiling point of pure water
at sea level. most people body temp is 37 degrees
Kelvin (K)
Used only in the scientific community. 0 degrees Kelvin is -273 degrees celsius and is thought to be
the lowest temp achievable, 273 degrees Kelvin is the freezing point of water, 373 degrees Kelvin is
the boiling point of water, most people body temp 310 degrees Kelvin but this is never used.
Absolute zero
0 degree Kelvin, -273 degrees Celcius. thought to be the lowest temp achievable
, Melting ice
21 degrees Celcius and 32 degrees Fahrenheit
Normal body temp
37 degrees Celcius and 98.6 degrees Fahrenheit
Boiling water
100 degrees Celcius and 212 degrees Fahrenheit
Atom
The basic building block of all molecules. most stable when an orbital is full. The simplest form of
matter that can naturally exist in nature.
Physical structure of an Atom
nucleus and orbits, which are sometimes called electron cloud.
Nucleus
at the center of the atom and composed of protons and neutrons
Orbits
sometimes called electron cloud, located at the outermost part of the atom and is where the
electrons are
Electron
spins around (orbits) the nucleus at various energy levels called orbits or shells so fast forming
electron clouds.
Shell or Orbits
various energy levels around the nucleus
Proton charge
has a positive electrical charge
Electron charge
has a negative charge
Neutron charge
has no charge at all
Ground state atom
tend to have equal numbers of protons and electrons making them electrically neutral.
Ion or Ionic state
An atom that is electrically charged (+ or -) either by losing or gaining electrons
Chemistry
The study of matter and its properties and how those properties relate to one another
Three states of matter
solid, liquid, gas
Scientific notation
The scientific system of writing numbers. A method to write very big or very small numbers easily. Is
composed of three parts: a mathematical sign, + or -, the significand, and the exponential, sometimes
called the logarithm.
Mathematical sign
designates whether the number is positive or negative
(+ or -)
Significand
the base value of the number or the value of the number when all the values of ten are removed
Exponential
A multiplier of the significand in powers of ten. Move the decimal in the significand the number of
places equal to the exponent of 10. positive to the right, negative to the left. Numbers between -1
and 1 always place a zero to the left of the decimal.
Temperature systems
Fahrenheit, Celsius, and Kelvin
Fahrenheit (F)
Used only in US, Belize, and Jamaica. 0 degrees is the freezing point of sea water or heavy brine at sea
level. 32 degrees is the freezing point of pure water at sea level, 212 degrees is the boiling point of
pure water at sea level. most people body temp s 98.6 degrees
Celsius (C)
sometimes called Centigrade and is used in the rest of the world and by the scientific community. 0
degree is the freezing point of pure water at sea level, 100 degrees is the boiling point of pure water
at sea level. most people body temp is 37 degrees
Kelvin (K)
Used only in the scientific community. 0 degrees Kelvin is -273 degrees celsius and is thought to be
the lowest temp achievable, 273 degrees Kelvin is the freezing point of water, 373 degrees Kelvin is
the boiling point of water, most people body temp 310 degrees Kelvin but this is never used.
Absolute zero
0 degree Kelvin, -273 degrees Celcius. thought to be the lowest temp achievable
, Melting ice
21 degrees Celcius and 32 degrees Fahrenheit
Normal body temp
37 degrees Celcius and 98.6 degrees Fahrenheit
Boiling water
100 degrees Celcius and 212 degrees Fahrenheit
Atom
The basic building block of all molecules. most stable when an orbital is full. The simplest form of
matter that can naturally exist in nature.
Physical structure of an Atom
nucleus and orbits, which are sometimes called electron cloud.
Nucleus
at the center of the atom and composed of protons and neutrons
Orbits
sometimes called electron cloud, located at the outermost part of the atom and is where the
electrons are
Electron
spins around (orbits) the nucleus at various energy levels called orbits or shells so fast forming
electron clouds.
Shell or Orbits
various energy levels around the nucleus
Proton charge
has a positive electrical charge
Electron charge
has a negative charge
Neutron charge
has no charge at all
Ground state atom
tend to have equal numbers of protons and electrons making them electrically neutral.
Ion or Ionic state
An atom that is electrically charged (+ or -) either by losing or gaining electrons
