Before you read A or D StatementAfter you read A or D Matter cannot be created or destroyed. The model of the atom has remained mostly unchanged since the idea of atoms was first proposed. Atoms contain mostly empty space. Two atoms of the same element might contain different numbers of neutrons If you are given the element name, you can determine the mass number of an atom. A mixture is a type of substance. Substances that contain the same elements will have the same chemical and physical properties. Both compounds and mixtures contain more than one type of element

3.1 Structure of Matter All types of matter are made of atoms. Atoms contain protons and neutrons in a tiny nucleus and electrons in a cloud around the nucleus

3.1 Structure of Matter What is matter? Anything that has mass and takes up space. What isn’t matter? Ex: light, heat, emotions, thoughts. None of these things take up space nor do they have mass What makes up matter? Atoms : small particles that make up most types of matter. brainpop-atoms

3.1 Structure of Matter HISTORY Democritus- 380 B.C. First to identify the universe made up of tiny particles he called atoms. Believed different types of atoms existed for every type of matter. His ideas were the first step toward understanding matter Lavoisier Law of conservation of matter which states that matter is not created or destroyed-it only changes form. Ex: When wood burns, matter is not lost. The total mass of the wood and the oxygen it combines with during a fire = the total mass of the ash, water vapor, carbon dioxide and other gases produced.

3.1 Structure of Matter HISTORY Atomic Models John Dalton’s Atomic Model- early 1800’s Believed matter was made of atoms too small to see Each type of matter was made of only one kind of atom Dalton’s ideas were supported by data His model became known as the atomic theory of matter J.J. Thomson Discovered the electron through his experiments with a cathode ray. Thomson’s Model shows the atom as electrons embedded in a ball of positive charge. “cookie dough”

3.1 Structure of Matter HISTORY Atomic Models Ernest Rutherford Experiments with gold foil Discovered protons exist in nucleus Theorized that electrons are scattered in the mostly empty space around the nucleus

3.1 Structure of Matter James Chadwick-1910 Discovered the neutron through his work with Rutherford Chadwick’s proton-neutron model of the atomic nucleus is still accepted today. Niels Bohr-1915 Suggested electrons move in energy levels

3.1 Structure of Matter The Modern Atomic Model Electron cloud Spherical cloud of varying density surrounding the nucleus Atoms with electrons in higher energy levels have electron clouds of different shapes Electron cloud has a radius about 10,000 times that of the nucleus.

3.1 Structure of Matter In Class Review Questions

3.1 Structure of Matter Vocabulary wordDefinition matter atom law of conservation of matter electron nucleus proton neutron density

*3.1 Structure of Matter Vocabulary wordDefinition matter (pg. 72) atom (pg. 73) law of conservation of matter (pg. 74) electron (pg. 76) nucleus (pg.77) proton (pg. 77) neutron (pg. 78) density

3.2 The Simplest Matter Vocabulary wordDefinition element atomic number isotope mass number atomic mass metal nonmetal metalloid

3.2 The Simplest Matter Element- matter made of only one kind of atom Some elements occur naturally on Earth Ex: gases such as oxygen and nitrogen Ex: metals such as gold, silver, aluminum and iron Other elements are synthetic elements Made by scientists with machines called particle accelerators

3.2 The Simplest Matter Periodic Table: Each element is represented by a chemical symbol that contains one to three letters. Ex: carbon is C, calcium is Ca. Elements are organized by their properties. Rows are called periods. The elements in a row have the same number of energy levels. Columns are called groups. The elements in each group have similar properties related to their structure.

3.2 The Simplest Matter Classification of Elements: Metals usually have a shiny or metallic luster good conductors of heat and electricity. all metals except for mercury are solids at room temperature. Malleable (can be bent and pounded into shapes) Ductile (drawn into wires without breaking Nonmetals Usually dull in appearance Poor conductors of heat and electricity Many are gases at room temperature 97% of human body is made up of nonmetals. Metalloids Characteristics of metals and nonmetals Solids at room temperature Many are conductors but not as good as metals. Silicon is a metalloid Interactive Periodic Table Website

3.2 The Simplest Matter Identifying Characteristics The top number is the element’s atomic number. This is how many protons are in the nucleus of each atom of that element. Ex: every atom of magnesium has 12 protons in its nucleus. Isotopes are atoms of the same element that have different numbers of neutrons. Ex: chlorine-35 and chlorine- 37. An atom’s mass number is the number of protons plus the number of neutrons it contains. Atomic mass is the weighted average mass of the isotopes of an element. This is the number found below the element symbol. The atomic mass of magnesium is

3.3 Compounds and Mixtures Vocabulary wordDefinition formula substance compound mixture

3.3 Compounds and Mixtures The food we eat, the materials we use and all matter can be classified by compounds or mixtures. Substance- matter that has the same composition and properties throughout. An element such as a bar of gold is a substance. Compound- a substance whose smallest unit is made up of atoms of more than one element bonded together. Properties that are different from the elements that make them up. Ex: water, H 2 O. Mixtures- when two or more substances (elements or compounds) come together but don’t combine to make a new substance. Ex: mixing sand and water together does not change its identity. They are not chemically bonded together.

3.3 Compounds and Mixtures Compounds Have Formulas Chemical formulas: Which elements make up a compound The subscript number written below and to the right of each element’s symbol tells how many atoms of each element are present Ex: H 2 O has two atoms of hydrogen and one atom of oxygen. Ex: H 2 O 2 has two atoms of hydrogen and two atoms of oxygen. *Propane has three carbon and eight hydrogen atoms. What is its chemical formula? Propane = C 3 H 8

3.3 Compounds and Mixtures Homogeneous Mixtures Homogenous means “the same throughout.” You cannot see the different parts in this type of mixture Ex: blood. Heterogeneous Mixtures Larger parts that are different from each other You can see the different parts in this type of mixture Ex: sand and water

Chapter 3 Review 1._____________ is anything that occupies space and has mass. 2.Matter is made up of ____________ which are made up of smaller parts called _____________, __________________, and ____________. 3.The modern ___________ model has a central ____________ with the protons and neutrons, and an _________ ____________ surrounding it. 4.The new substance formed when elements combine chemically is a(n)_________________. 5.Elements that are shiny, malleable, ductile, good conductors of heat and electricity are ________________.

Review Questions Pg Answer #1-20 on loose leaf. To be collected and graded. Homework if not finished in class.