Ch 2 Matter & Energy CHEMISTRY

What is Matter? Everything in the world is made up of matter! Anything that has mass and takes up space is matter. You are made of matter, milk is matter, air is matter Matter is made up of tiny particles called atoms. Atoms are the smallest building blocks of all matter. They are extremely small! Chemistry is the study of matter and the changes that happen with matter. Matter can be described by its physical properties or chemical properties.

Physical Properties of Matter: 1.Physical properties: –Properties that can be looked at without changing the matter. –Appearance, hardness, odor, density, viscosity, electrical conductivity, boiling point, melting point, color, shape etc. Physical changes – change the physical form of matter without changing its chemical identity –Melting ice –Dissolving sugar in water –Ripping, tearing, breaking Boiling water does not change the make-up of the matter, it is still H20.

Some Physical Properties Phase (solid, liquid, gas) Mass Volume Density Melting Point Boiling Point Volatility Malleability Ductility Taste Odor Color Texture Shape Solubility Electrical Conducting Heat Conducting Magnetism

Chemical Properties of Matter: Chemical property- tells how matter reacts with other matter (Flamability, combustable, corrosive, etc.) Chemical change – the chemical identity of a substance is destroyed and a new substance(s) is formed –Rusting of iron –Baking a cake –Digesting of food –Burning paper

Some Chemical Properties Acidity Corrosiveness Reactivity Inertness Flammability Oxidizing Ability Stability Explosiveness Combustibility Sensitivity to Light

Chemical Changes A chemical change is a process where one substance changes into another. Chemical changes can give off heat, light or electricity. A chemical change can take in heat (endothermic) or give off heat (exothermic) Matter cannot be created nor destroyed. This is known as the law of conservation of matter. Energy cannot be created nor destroyed. This is known as the law of conservation of energy.

Matter can be PURE or MIXED:

Mixtures can be separated… Distillation – based on boiling pointFiltration – based on size Elements and Compounds CANNOT

Elements All atoms of the same element have the same number of protons in the nucleus. The atomic number tells how many protons there are in the nucleus.All atoms of the same element have the same number of protons in the nucleus. The atomic number tells how many protons there are in the nucleus. Al Atomic number Element symbol Atomic Mass

Compounds –composed of 2 or more elements in a fixed ratio (H20, water) –properties differ from those of individual elements –example: table salt (NaCl)

Molecules A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound.A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound. The make-up of molecules is shown by a CHEMICAL FORMULA C8H10N4O2 - caffeine H2O -water