1: Matter consists of chemical elements in pure
form and in combinations called compounds
Matter is anything that takes up space and has mass.
Matter exists in various forms, including rocks, metals, oils, gases, and living
organisms.
Living organisms, including plants and animals, are a type of matter.
Elements and Compounds
Matter is made up of elements that cannot be broken down by chemical
reactions.
There are 92 elements occurring in nature, such as gold, copper, carbon, and
oxygen.
Sodium chloride (NaCl) is an example of a compound, with sodium (Na) and
chlorine (Cl) in a 1:1 ratio.
Compounds have emergent properties different from their constituent
elements.
Water (H2O) is a compound composed of hydrogen (H) and oxygen (O) in a
2:1 ratio.
The Elements of Life
Approximately 20-25% of the 92 natural elements are essential for
organisms to live and reproduce. Humans need 25 elements, while plants
need 17.
Oxygen, carbon, hydrogen, and nitrogen make up about 96% of living
matter. Calcium, phosphorus, potassium, sulfur, and a few other elements
account for the remaining 4%.
Trace elements are required in small quantities, with some needed by all
forms of life and others only by certain species.
2: An element’s properties depend on the structure
of its atoms
Each element consists of a specific type of atom, highlighting the uniqueness
of each element.
An atom is the smallest unit of matter that retains the properties of an
element.
, Atoms are incredibly small, with about a million needed to stretch across a
period.
Atoms are symbolized using the same abbreviation as the element they
make up.
Subatomic Particles
Atoms are composed of subatomic particles: neutrons, protons, and
electrons.
Protons and electrons are electrically charged, with protons having a
positive charge (+) and electrons (-) having a negative charge. Neutrons
are electrically neutral.
Protons and neutrons are tightly packed in the atomic nucleus, giving it a
positive charge.
Electrons move rapidly around the nucleus, forming a cloud of negative
charge.
The attraction between opposite charges keeps the electrons in the vicinity
of the nucleus.
The mass of an electron is much smaller than that of a neutron or proton, so
it can be ignored when computing the total mass of an atom.
The mass of subatomic particles is measured in daltons, which is the same
as the atomic mass unit (amu).
Atomic Number and Atomic Mass
Atoms of different elements have varying numbers of subatomic particles.
The atomic number, unique to each element, indicates the number of
protons in an atom's nucleus.
An atom is electrically neutral, with the number of protons balanced by
electrons.
The mass number represents the total protons and neutrons in an atom's
nucleus.
Neutrons can be calculated by subtracting the atomic number from the mass
number.
Atomic mass slightly differs from the mass number due to electron
contribution.
Isotopes
All elements have isotopes, which are different atomic forms with varying
numbers of neutrons.
form and in combinations called compounds
Matter is anything that takes up space and has mass.
Matter exists in various forms, including rocks, metals, oils, gases, and living
organisms.
Living organisms, including plants and animals, are a type of matter.
Elements and Compounds
Matter is made up of elements that cannot be broken down by chemical
reactions.
There are 92 elements occurring in nature, such as gold, copper, carbon, and
oxygen.
Sodium chloride (NaCl) is an example of a compound, with sodium (Na) and
chlorine (Cl) in a 1:1 ratio.
Compounds have emergent properties different from their constituent
elements.
Water (H2O) is a compound composed of hydrogen (H) and oxygen (O) in a
2:1 ratio.
The Elements of Life
Approximately 20-25% of the 92 natural elements are essential for
organisms to live and reproduce. Humans need 25 elements, while plants
need 17.
Oxygen, carbon, hydrogen, and nitrogen make up about 96% of living
matter. Calcium, phosphorus, potassium, sulfur, and a few other elements
account for the remaining 4%.
Trace elements are required in small quantities, with some needed by all
forms of life and others only by certain species.
2: An element’s properties depend on the structure
of its atoms
Each element consists of a specific type of atom, highlighting the uniqueness
of each element.
An atom is the smallest unit of matter that retains the properties of an
element.
, Atoms are incredibly small, with about a million needed to stretch across a
period.
Atoms are symbolized using the same abbreviation as the element they
make up.
Subatomic Particles
Atoms are composed of subatomic particles: neutrons, protons, and
electrons.
Protons and electrons are electrically charged, with protons having a
positive charge (+) and electrons (-) having a negative charge. Neutrons
are electrically neutral.
Protons and neutrons are tightly packed in the atomic nucleus, giving it a
positive charge.
Electrons move rapidly around the nucleus, forming a cloud of negative
charge.
The attraction between opposite charges keeps the electrons in the vicinity
of the nucleus.
The mass of an electron is much smaller than that of a neutron or proton, so
it can be ignored when computing the total mass of an atom.
The mass of subatomic particles is measured in daltons, which is the same
as the atomic mass unit (amu).
Atomic Number and Atomic Mass
Atoms of different elements have varying numbers of subatomic particles.
The atomic number, unique to each element, indicates the number of
protons in an atom's nucleus.
An atom is electrically neutral, with the number of protons balanced by
electrons.
The mass number represents the total protons and neutrons in an atom's
nucleus.
Neutrons can be calculated by subtracting the atomic number from the mass
number.
Atomic mass slightly differs from the mass number due to electron
contribution.
Isotopes
All elements have isotopes, which are different atomic forms with varying
numbers of neutrons.
