CHEMISTRY INTRODUCTION TO MATTER

ENDURING UNDERSTANDINGS All matter is composed of atoms. Chemistry is the study of the properties of matter and how matter changes. Energy is the ability to do work or cause change.

Properties of MATTER? Matter is anything that takes up space and has mass. Matter is described by its properties.

1. Physical properties are characteristics of pure substances that change form without changing chemical composition. 2. Chemical properties are observed when substances become new substances with new chemical compositions.

CHEMICAL & PHYSICAL PROPERTIES Name several chemical properties of matter… Name several physical properties of matter… freezing and boiling temperatures, texture, dissolves in water, luster, color, conductivity, state of matter, hardness flammability, rusting, ability to combine with other elements to form new substances

B. ELEMENTS 2. Elements are the simplest substances. 1. An element is a pure substance that cannot be broken down into smaller parts. 3. Elements are arranged on the Periodic Table by their physical and chemical properties.

The smallest particle of an element is the atom. 5. An atom has a positively-charged nucleus surrounded by a negatively-charged cloud of electrons.

ELEMENTS & ATOMS 6. A chemical bond is the force that holds two atoms together. 7. A molecule is 2 or more atoms joined together that act as a single unit.

C. COMPOUNDS 1. A compound is formed when two or more different elements chemically combine. Table salt is composed of NaCl Seashells are composed of CaCO 3 2. A compound can have completely different properties than the elements that have formed it. 3. A chemical formula represents the compound.

D. MIXTURES 2. In heterogeneous mixtures you can see the different ingredients. Juices & soft drinks are homogenous mixtures Rocks are heterogeneous mixtures of minerals 1. Mixtures are two or more substances physically but not chemically combined. 3. In homogenous mixtures, parts are too well mixed to see separately. Solutions are homogenous mixtures.

... compounds cannot. Mixtures can be “undone”…

WEIGHT VS MASS Mass is the amount of matter in an object. Weight is the force of gravity on an object's mass. Your mass would be the same on the moon as on Earth, but your weight would change… why?

INTERNATIONAL SYSTEM OF UNITS - "SI" The SI unit for... is the... mass volume length meter kilogram liter

VOLUME Volume is measured as length x width x height Volume is the amount of space matter occupies Volume is expressed as cm 3

DENSITY Density is the measure of the mass contained within a given volume… gasesliquidssolids Compare the densities of… Or in other words, how tightly the atoms are packed.

FIGURING DENSITY Density = Density is expressed as g/cm 3 Wa ter has a density of 1 g/cm 3 A small block of wood floats on water. It has mass of 200g and volume 250m 3. What is the density of the wood? mass volume 200g / 250cm 3 = 0.80 g/cm 3

CHANGES IN MATTER Physical change alters the form or appearance of matter but does not change a substance into a different substance. Examples of physical change include changes of state, such as freezing and melting, and changes in shape or form, like crushing a can or cutting a piece of paper.

200g / 250cm 3 = 0.80 g/cm 3 Chemical change forms new substances with different chemical compositions.

200g / 250cm 3 = 0.80 g/cm 3 LAW OF CONSERVATION OF MASS No mass is lost or gained during a chemical or physical reaction, only rearranged. The number of atoms on each side is the same, but they have been rearranged.

MATTER & THERMAL ENERGY Energy is the ability to do work or cause change. Every chemical or physical change includes a change in energy. Temperature is the measure of energy in particles. Thermal energy is the total energy of all the particles in an object.

THERMAL ENERGY & CHANGES IN MATTER During an endothermic change, energy is absorbed by a substance from its surroundings. Melting is an endothermic change. During an exothermic change, energy is released by a substance into its surroundings. Burning is an exothermic reaction.

FORMS OF ENERGY Kinetic energy - E nergy of motion Potential energy - S tored energy due to position Chemical energy - E nergy stored in chemical bonds between atoms

Electromagnetic energy - E nergy that travels in waves Electrical energy - E nergy of electrically charged particles, electrons, moving from one place to another Thermal energy - T otal energy of all particles in an object

ENERGY TRANSFORMATIONS Energy can be changed from one form to another. For instance, the burning of a match transforms chemical energy into electromagnetic and thermal energy. The most common energy transformation is potential energy to kinetic energy.