Before you readA or D

Statement After you readA 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

3.1Structure 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

3.1Structure 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

3.1Structure 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- 1772-1794 • 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.

3.1Structure 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- 1894• 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”

3.1Structure of Matter

HISTORY• Atomic Models

• Ernest Rutherford -1910• Experiments with gold foil• Discovered protons exist in nucleus• Theorized that electrons are scattered in the mostly

empty space around the nucleus

3.1Structure 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

3.1Structure 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.

3.1Structure of Matter

In Class Review Questions

3.1 Structure of MatterVocabulary word Definition

matter

atom

law of conservation of matter

electron

nucleus

proton

neutron

density

*3.1 Structure of MatterVocabulary word Definition

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 MatterVocabulary word Definition

element

atomic number

isotope

mass number

atomic mass

metal

nonmetal

metalloid

3.2The 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

3.2The Simplest MatterPeriodic 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.

3.2The 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 24.305.

3.3 Compounds and MixturesVocabulary word Definition

formula

substance

compound

mixture

3.3 Compounds and MixturesThe 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, H2O. • 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 MixturesCompounds 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: H2O has two atoms of hydrogen and one atom

of oxygen.• Ex: H2O2 has two atoms of hydrogen and two

atoms of oxygen.• *Propane has three carbon and eight hydrogen

atoms. What is its chemical formula?

Propane = C3H8

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 96-97

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