10. Examples of Physical & Chemical Changes You fry an egg. Your body digests food. You take an antacid to settle your stomach. A match is lit. Food scraps turn into compost. Hydrogen peroxide bubbles in a cut. Rubbing alcohol evaporates on your hand. Gasoline is ignited. A juice box in the freezer freezes. Rust forms on a nail left outside. Water evaporates from the ocean's surface. Bread becomes toast. Butter melts on warm toast. Jewelry tarnishes. Clay is molded into a new shape. Milk goes sour. Aluminum foil is cut in half. Chemical Changes Physical Changes
Notas do Editor
chalk = calcium carbonite (CaCH3) ammonia = NH3
Jell-O is a colloid: a heterogeneous mixture with particles larger than those in a solution, but not large enough to settle out. Milk, paint, and mayo are, too (and aerosols).
Quick review on rounding to a whole number: Jeanne's method: circle the one's place number draw arrow to number on the right if it's 5 or above, the circled number is raised one digit if it's 4 or below, the circled number STAYS THE SAME In the example here, round the mass to 96. Neutrons = 96-42 = 54 Isotopes: One of two or more atoms that have the same atomic number (the same number of protons) but a different number of neutrons. Carbon 12, the most common form of carbon, has six protons and six neutrons, whereas carbon 14 has six protons and eight neutrons. Isotopes of a given element typically behave alike chemically. With the exception of hydrogen, elements found on Earth generally have the same number of protons and neutrons; heavier and lighter isotopes (with more or fewer neutrons) are often unstable and undergo radioactive decay .
Don't go into too much detail at this point about valence electrons and reactivity.