Properties of Matter What are living things made of? Are there special substances found in living things but not in nonliving material? Forms of matter have properties (ie: characteristics) in which they are identified

Physical properties MATTER: anything that has mass and volume. MASS: quantity of matter in an object VOLUME: amount of space matter takes up. An object has weight because it has mass mass ≠ weight WEIGHT: measure of the force of gravity of an object › mass › force of gravity › weight weight is directly proportional to its mass

Physical properties cont…. Color, shape, texture, taste, and hardness Melting point Boiling point Physical properties of matter can be observed and measured without permanently changing the identity of the matter

Physical Changes in Matter change in a substance that doesn’t change the identity of the substance Ex. grinding, cutting, melting, boiling Includes all changes of state (physical changes of a substance from one state to another)

Chemical properties Describe a substance’s ability to change into another new substance as a result of a chemical change. A substance is permanently altered Almost impossible to reverse

Phases of Matter Matter that have exactly the same substances, but in different states Physical property because the substance is not altered Ex: ice, water, vapor

Solid » definite volume » definite shape » atoms are packed together in fixed positions » strong attractive forces between atoms » only vibrate in place

Liquid » definite volume » indefinite shape » atoms are close together » atoms can overcome attractive forces to flow

Gases » indefinite volume » indefinite shape » atoms move very quickly » atoms are far apart » pretty weak attractive forces

Matter and Energy Energy- the ability to do work or to put matter into motion.  Kinetic energy- Energy doing work (moving an object)  Ex. A student pushing a desk  Potential energy- When energy is inactive or stored  Ex. A ball resting at the top of a steep slope, just before it begins to roll

Matter and Energy Forms of energy  Chemical energy is stored in the bonds of substances  When bonds are broken, the potential energy stored in the bonds is released and becomes kinetic energy.  Example?  Electrical energy is the movement of charged particles  Ex: electricity flowing through a wire  Mechanical energy is DIRECTLY involved in moving matter  Ex: Arms providing the energy to lift a stack of books  Radiant energy travels in waves and is the energy of the electromagnetic spectrum  Ex: Can you think of an example of radiant energy?

Energy can be converted from one form to another  Mechanical to electric, radiant to electric, chemical to mechanical, etc. Energy conversions are inefficient  Some of the initial energy is always lost as heat to the environment  Ex: Light bulb- electrical energy to radiant energy (light), heat is given off.  Energy conversions in our bodies give off excess heat vital to our survival Matter and Energy

Composition of Matter ATOM: basic, indivisible particles. Smallest particle of matter that can still exist and still have the properties of a particular kind of matter (ie: basic unit of matter) Atom is made up of SUBATOMIC particles 1. electron 2. proton 3. neutron

Atomic Structure NUCLEUS: center of an atom that contains… PROTON: positively charged particle NEUTRON: electrically neutral particle

Atomic Structure cont…. Not in nucleus, but travel in energy levels AROUND nucleus…. ELECTRON: negatively charged particle Electron = Proton → Neutral

Atomic Number and Mass Number ATOMIC NUMBER: = the number of protons Atomic number is unique to each element Match the atomic number (ie: number of protons) to the number on the periodic table to determine what element it is. # protons in nucleus of every atom in an element stays the same MASS NUMBER: # protons + # neutrons

Chemical Elements Elements are ONE type of atom ONLY Represent elements by a symbol Refer to periodic table

Isotopes Atom of an element that has a different number of neutrons than other atoms of the same element # protons stay the same in every atom, BUT the # neutrons can differ Can have different mass #, BUT atomic # stays the same

Chemical Compounds When elements combine to form substances consisting of two or more different atoms Represented by a chemical formula Ex: 2 atoms Hydrogen + 1 atom of oxygen = water H₂O =

Interactions of Matter Combining atoms of elements are how chemical compounds form… CHEMICAL BONDING Atoms combine according to certain rules that are determined by the number of electrons in the nucleus…’specially in the outermost level

Energy levels (see fig 3-12 p.52) Energy level #1 = 2 electrons Energy level #2 = 8 electrons Energy level #3 = 8 electrons or 18 (look on periodic chart at the end of each row)

Energy levels cont… When outermost level has max number electrons the atom is very stable When an atom is stable (ie: outermost level full) it does NOT combine with other atoms to form compounds Goal of all atoms is to become stable, therefore they will gain or lose electrons to achieve stability Atom will bond to another IF the bonding results in a complete outermost energy level

Ionic Bonds (see fig 3-13 p.53) Transfer of electrons from one atom to another Opposites attract (positive +/negative-)

Ionic Bonds Bonds where electrons completely transfer from one atom to another  This creates ions, or charged particles More electronegative atom gains electrons and becomes more negative  Anion Less electronegative atom loses electrons and becomes more positive  Cation Opposite charges (the anion and cation) attract, creating an ionic bond Ex: Formation of NaCl (common table salt) Na less electronegative, so loses electron and becomes cation (Na+) Cl more electronegative, so steals electron and becomes anion (Cl-) Opposite charges attract, forming NaCl Remember Rule of 8s!

Covalent Bonds When a chemical bond is formed by the sharing of electrons By sharing, each atom fills its outermost level Can be single, double, or triple depending on number of electrons shared

Molecules Combination of atoms that form a separate unit Smallest particle of a covalently bonded compound

Lewis Structures Simple way to visually show how atoms in a molecule are bonded together  In this class, we will only do Lewis Structures of covalent bonds  Remember the rule of 8s! Steps 1. Find out how many valence electrons each atom has in molecule 2. Arrange atoms so that the least abundant and then least electronegative atom is in the center 3. Draw known valence electrons around each atom 4. Draw a single bond between each atom, if every atom has an octet, you are done 5. If not, draw double bonds between the atoms until every atom has an octet

Lewis Structure Example Water, or H20 1. Hydrogen=1, hydrogen=1, oxygen=6 2. H O H

Carbon Dioxide, or CO2 Lewis Structure Example