The Big Question: What are properties of Matter? Students will use models to investigate that matter is made up of particles that are too small to be seen. Lesson 1

Matter Anything that has mass and takes up space. Is air matter? Yes because air is made up of gases which are made up of atoms and have an atomic mass. When you blow up a balloon you can see it takes up space.

Atoms Proton (nucleus) Positive charge + Neutron (nucleus) Neutral no charge Most of the mass Electron (outside nucleus) Negative charge – Atoms are neutral because they have tha=e same number of protons and electrons

Drawing of an Atom

Atoms have a tendency to gain or lose electrons If an atom gains an electron it becomes a negatively charged ion If an atom loses an electron it becomes a positively charged ion Atoms are the smallest part of matter. If 100,000,000 atoms were lines up, the row would only measure about 1 cm long.

Atoms are mostly empty space where electrons move in the area around the nucleus. Protons and neutrons have about the same mass; they are about 1,840 x the mass of an electron.

Elements Around 450 BCE, Greek philosopher, Empedocles, proposed all matter was a combination of two or more of the four elements: air, earth, fire and water. Late 1600’s scientist discovered that matter was made up of much more. Now scientist know there are more than 100 elements that make up all matter. In addition to natural occurring elements, many elements are made by humans.

Elements cannot be separated into a simpler substance. Each element has unique characteristics such as boiling point or density.

Periodic Table In the late 1800’s Russian scientist, Dmitri Mendeleev, discovered a repeating pattern with the known elements when they were arranged in order by increasing atomic mass(nucleus). They were “periodic” (repeating and regular pattern) Each square of the periodic table displays the element’s name, chemical symbol, atomic weight and atomic number.

Explain the layout and meaning of each part of the square on the periodic table. 6 – atomic number C – element Symbol Carbon – element name 12 – atomic number Atomic number = the number of protons in the element Atomic mass – number of protons and neutrons Equal number of protons and electrons

Molecules Elements can be combined to form particles known as molecules: 2 hydrogen + 1 oxygen + H2O

Compounds A compound is a pure substance made up of 2 or more elements that are chemically combined. Salt is a common compound : sodium chloride (NaCl) Sodium – soft, shiny metal Chlorine – greenish, poisonous gas Mixed together they make common table salt.