• Experimental science vs. Historical science
• Experimental Science is an exploration of science using the testing of ideas.
• experent: a scientific testing of a hypothesis
• control experiment: an experiment where you control all the variables
• Historic Science ia n exploration of science that is an investigation into events that happened in the far past.
• observation of nautre

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• https://www.nps.gov/grca/learn/nature/grca-geology.htm

VOCAB WORDS – UNIT 3

• Controlled experiment
• Experiment
• Experimental science
• Greenhouse effect
• Historical science
• Hypothesis
• Natural law
• Natural resource

• Nonrenewable resource
• Plate tectonics
• Oceanic circulation
• Renewable recourse
• Scalability
• Scientific fact
• Stewardship
• theory

The Periodic Tables

Use the terms below to complete the concept map on the next slide.

Concept Map

The Periodic Table

The Periodic Table

Combining Atoms Through Chemical Bonding

• Chemical bonding is the joining of atoms to form new substances.

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• An interaction that holds two atoms together is called a chemical bond. When chemical bonds form, electrons are shared, gained, or lost.

Chapter L1

Combining Atoms Through Chemical Bonding, continued

• Discussing Bonding Using Theories and Models We cannot see atoms and chemical bonds with the unaided eye.

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• So, the use of models helps people discuss the theory of how and why atoms form bonds.

Chapter L1

Electron Number and Organization

• The number of electrons in an atom can be determined from the atomic number of the element.

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• Electrons in an atom are organized in energy levels.

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• The next slide shows a model of the arrangement of electron in an atom. This model and models like it are useful for counting electrons, but do not show the true structure of an atom.

Chapter L1

Electron Number and Organization, continued

• Outer-Level Electrons and Bonding Most atoms form bond using only its valence electrons, the electrons in an atom’s outermost energy level.

Electron Number and Organization, continued

• Valence Electrons and the Periodic Table You can use the periodic table to determine the number of valence electrons for atoms of some elements, as shown on the next slide.

To Bond or Not to Bond, continued

• Filling the Outermost Level An atom that has fewer than 8 valence electrons is more likely to form bonds than at atom that has 8 valence electrons is. Atoms bond by gaining, losing, or sharing electrons to have a filled outermost energy level.

Forming Ionic Bonds

• An ionic bond is a bond that forms when electrons are transferred from one atom to another atom.

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• But when an atom gains or loses electrons, it becomes a charged particle called an ion.

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• When ions bond, they form a repeating three-dimensional pattern called a crystal lattice, such as the one shown below.

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• Properties of ionic compounds include brittleness, high melting points, and high boiling points.

Covalent Bonds

• A covalent bond forms when atoms share one or more pairs of electrons.

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• Substances that have covalent bonds tend to have low melting and boiling points.

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• Covalent bonds usually form between atoms of nonmetals, such as the atoms shown on the next slide.

Covalent Bonds, continued

• One way to represent atoms and molecules is to use electron-dot diagrams. An electron-dot diagram shows only the valence electrons in an atom.

Metallic Bonds

• A metallic bond is a bond formed by the attraction between positively charged metal ions and the electrons in the metal.

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• Movement of Electrons Throughout a Metal Bonding in metals is a result of the metal atoms being so close to one another that their outermost energy levels overlap. This overlapping allows valence electrons to move throughout the metal.

STATE CHANGES

◆ Solid to Liquid

• The process of changing state, such as melting ice, requires that energy be transferred in the form of heat.

• Latent heat is the energy absorbed or released during a change in state.

STATE CHANGES

◆ Liquid to Gas

• Evaporation is the process of

changing a liquid to a gas.

• Condensation is the process

where a gas, like water vapor,

changes to a liquid, like water.

STATE CHANGES

◆ Solid to Gas

• Sublimation is the conversion of a solid directly to a gas without passing through the liquid state.

• Deposition is the conversion of a vapor directly to a solid.

CHANGES OF STATE

CHEMICAL CHANGE

• A chemical change happens when one or mor substances are changed into a new substance. Or. . . . . A CHEMICAL REACTION!!!
• Examples of chemical change
• Fire
• Rotting
• Rust
• Cooking