Chemistry Unit Objective 4.02 The goal is to be able to evaluate evidence that elements combine in multiple ways to produce various substances

Complete the following How do you know whether a substance is a compound or a mixture? What factors need to be present?

Review of Compounds Compound—two or more substances chemically combine to form a new substance – Have a definite composition---NaCl is always table salt – Can be broken down into simpler substances by chemical means meaning NaCl can be broken into Na and Cl – Can be identified by their physical properties meaning how you observe it and measure it

Molecules smallest unit of a compound that has all the properties of the compound Ex smallest molecule of water would be H 2 O

Chemical Formula Chemical formula—the makeup of a compound, uses chemical symbols and subscripts to identify the number of atoms of each element in a molecule of a compound Ex. H and O are chemical symbols of hydrogen and oxygen 2 the subscript for the number of hydrogen atoms needed to bond with oxygen to make water…this is the formula for water H 2 O When there is not a subscript for a symbol that means there is only 1 atom present, you need one sodium and one chlorine to make salt the chemical formula is NaCl

A CHEMICAL FORMULA IS LIKE A _______ TO A _______

Atom Atom—smallest unit of an element that has the properties of the element, also called the building block of an matter

Parts of an Atom Proton—a particle with a positive charge (+) Neutron—a particle without a charge (neutral) ( ) Electron—a particle with a negative charge (-)

Location Nucleus of Atom contains protons and neutrons Randomly moving around the nucleus are the electrons nucleus

More on Electrons Electrons orbit the nucleus in a region called the electron cloud Electrons have different amounts of energy The closest electrons have less energy than electrons farther from the nucleus Electrons on the same energy level have similar amounts of energy

Electrons cont. Energy LevelMax Number of Electrons

How many valence electrons? Hydrogen Fluorine Neon Boron Beryllium Carbon Nitrogen Oxygen Lithium

Electrons…. Valence electrons are found in the outer shell of the atom – To determine how atoms combine to make compounds is dependent upon the number and arrangement of valence electrons

Atomic number=number or protons i.e…27 – Number of protons =number of electrons i.e…27 Atomic mass(weight) = number of protons + number of neutrons – i.e…58.93 Symbol=abbreviation of element original name i.e…Co Neutrons=atomic mass- atomic number i.e…58- 27=31 neutrons

COMPLETE ATOMS FAMILY WORKSHEET

Chemistry Unit Objective 4.02 The goal is to be able to evaluate evidence that elements combine in multiple ways to produce various substances

Complete the following Write a Haiku about the bond between friends After you have completed your poem explain how you feel this relates to atoms bonding

Chemical Bond Forces that hold atoms together To bond atoms need to have a total of eight electrons in their outer energy level Atoms with 1, 2, or 3 valence electrons normally give their electrons to atoms of elements that have 7, 6, or 5 valence electrons Atoms with 4,5,6, or 7 electrons tend to share electrons

Ionic Bonds when a bond is formed by losing or gaining electrons – Ion—atom that has gained or lost one or more electrons Losses electrons—atom becomes positive (+) Gains electrons—atom becomes negative(-) Form because opposite charges attract(+ -) – Ex NaCl metal+nonmetal

Covalent Bond atoms share valence electrons Form between elements whose atoms have 4, 5, 6, or 7 valence electrons nonmetal+nonmetal

Elemental Combinations The same elements and be combined differently to form different elements – Ex. H 2 O=water, H 2 O 2 =hydrogen peroxide; CO=carbon monoxide, CO 2 = carbon dioxide

Lewis Structure This is a website with examples of how to create a Lewis structure

Atomic Theory All matter is composed of atoms (building block) Atoms of a given element are identical—same number of protons and electrons Atoms of different elements combine in simple whole-number ratios to form chemical compounds—determined by valence electrons Compounds can make up living or nonliving substances Living—proteins, carbohydrates, fats Nonliving—plastics, rubber, medicines

MOLECULAR MODEL LAB