2.2 Mass, Matter, and Atoms 1

Chapter 2 Objectives Express lengths in metric and English units. Convert measurements and calculated quantities between different units. Calculate the surface area and volume of simple shapes and solids. Work with time intervals in hours, minutes, and seconds. Describe two effects you feel every day that are created by mass. Describe the mass of objects in grams and kilograms. Use scientific notation to represent large and small numbers. Design a controlled experiment. Create and use a graphical model based on data.

Chapter 2 Vocabulary element English system experimental variable exponent friction gas graph graphical model independent variable inertia length liquid mass metric system mixture plasma precision procedure scientific notation SI system solid speed surface area time interval variable volume weight x-axis y-axis

Inv 2.2 Time Investigation Key Question: How do we measure and describe time? 4

2.2 Mass, Matter, and Atoms Mass is the amount of “stuff” an object contains. Two effects mass has on matter: Weight is the force of the Earth’s gravity pulling down. Gravity acts on an object’s mass. Inertia is the tendency of an object to resist changes in motion. Inertia comes from mass.

2.2 Measuring mass Kilogram is the mass of 1 liter of water or 1,000 cubic centimeters of water.

2.2 Very large and very small numbers Because physics covers such a wide range of values for length, time, and mass you will need a method of working with large and small numbers. In scientific notation, numbers are written as a value between 1 and 10, multiplied by a power of 10 called the exponent.

2.2 Matter and atoms A single atom is about 10-10 meters in diameter. Aluminum foil is thin but still more than 200,000 atoms thick. Whether matter is a solid, liquid, or gas depends on how the atoms are organized.

2.2 Matter and atoms Solids - Atoms in a solid stay together because the energy per atom is too low to break the bonds between atoms. Liquids - Liquids flow because atoms have enough energy to move around by temporarily breaking and reforming bonds with neighboring atoms. Gases - Gas atoms have enough energy to completely break bonds with each other. Plasma - In plasma, matter becomes ionized as electrons are broken loose from atoms.

2.2 The diversity of matter There is an incredible diversity of matter around you. This diversity comes from combining elements into compounds, then compounds into mixtures of compounds.

2.2 The diversity of matter Each type of matter is called an element. Each element has is own properties, such as mass and the ability to combine with other elements. There are about 92 different types of atoms in ordinary matter.

2.2 The diversity of matter A compound is a substance that contains two or more different elements bonded together. Water is an example of a compound. If you could look at water with a powerful atomic microscope you would find each particle of water is made from one oxygen atom and two hydrogen atoms.

2.2 The diversity of matter Another compound, glucose, is a sugar in food. A single glucose molecule is made of carbon, oxygen, and hydrogen atoms.

2.2 Matter and atoms The matter you normally experience is made of mixtures of compounds. Wood is a mixture that contains water and more than 100 other compounds.