PA Assessment Anchor and Eligible Content: S11. A. 3. 3 PA Assessment Anchor and Eligible Content: S11.A.3.3.2: Compare stationary physical patterns to the objects properties. KEY CONCEPT All living things are based on atoms and their interactions.

What are living things made of? Nature of Matter What are living things made of? All living & nonliving things are made of matter. Matter has both physical and chemical properties.

Physical Properties Physical properties are those properties that can be observed and measured without changing the identity of the substance. Two physical properties are used to define matter: Matter is anything that has mass and volume.

Physical Properties Volume is the amount of space matter occupies. Mass is the quantity of matter in an object. (An object has weight because it has mass. Weight is a measure of the force of gravity) Volume is the amount of space matter occupies.

Other physical properties of matter include: color odor shape texture taste hardness melting point boiling point

Chemical Properties Chemical properties describe a substance’s ability to change into another new substance as a result of a chemical change. With a chemical change a substance is permanently altered (e.g., burning wood).

States (or Phases) of Matter In nature matter usually occurs in three different forms or states. (1) Solid -- holds its shape and volume even when not in a container (molecules are tightly compacted). (2) Liquid -- assumes the shape of its container (molecules are in constant motion & don’t have a fixed shape).

States (or Phases) of Matter (3) Gas -- has no shape and assumes the full-volume shape of any closed container. .

States (or Phases) of Matter Matter undergoes a change of state (or phase change) when it physically changes from one form to another. It is a physical change because the substance is not altered. For example, water, regardless of its state (liquid, ice, or steam) is still water.

Composition of Matter Matter can be divided down to the level of the atom. Therefore, the basic unit of matter is the atom. The word atom comes from the Greek word atomos, meaning unable to be cut.

Atomic Structure The center of the atom is called the nucleus. It makes up 99.9% of the mass of the atom. It contains subatomic particles called protons and neutrons.

Atomic Structure The proton has a positive charge (+). The size of a proton is 1 amu (atomic mass unit). The neutron has no charge. It is electrically neutral. The size of a neutron is 1 amu.

Atomic Structure Energy levels surround the nucleus. They contain electrons which are not found in the nucleus. The electron is a negatively charged (-) particle. The electron is extremely tiny in size (1/1836 amu).

Atomic Structure Under normal conditions the atom has a neutral charge: electrons(-) = protons(+) Atomic number is the number of protons in the nucleus. Atomic number is used to identify an atom (e.g. carbon’s atomic number is 6)

Atomic Structure Atomic mass number is the total number of protons & neutrons in the nucleus. For example, carbon’s atomic mass number is 12

Carbon Atom

Atomic Structure

Chemical Element A chemical element consists of only one type of atom. Scientists have identified 117 different elements. 94 types of elements are found in nature, the other 23 have been artificially produced.

Chemical Element Each element is represented by a chemical symbol which has 1 or 2 letters. For example: C = carbon; Na = sodium

Isotopes Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. The nuclei of some atoms are unstable & will break down, releasing matter and/or energy called radiation.

Isotopes

Isotopes Radioactive isotopes have many uses: (1) They are used to study living things (2) To diagnose & treat diseases (3) To sterilize foods (4) To measure the age of certain rocks Radiation can harm or kill living things.

Molecule & Chemical Compounds A molecule consists of two or more atoms covalently bonded. A chemical compound consists of two or more different atoms. A chemical compound is represented by a chemical formula. (e.g. water is H2O)

Chemical Compounds

Interactions of Matter Chemical compounds are formed when atoms combine in a process called chemical bonding. Atoms combine depending on the number of electrons in the outermost energy level. Each energy level can hold only a certain number of electrons.

Interactions of Matter The first energy level can hold only 2 electron. The outermost energy level (the 2nd or 3rd level) can hold 8 electrons. When the outermost energy level has 8 electrons it is full or complete.

Interactions of Matter

Ionic Bonds A bond that involves a transfer of electrons is called an ionic bond. Ions (charged atoms) are formed when an ionic bond occurs. The strong attraction between oppositely charged ions holds the ions together in an ionic bond.

Ionic Bonds