Chemistry Properties of Matter What is Matter Matter

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Chemistry Properties of Matter

Chemistry Properties of Matter

What is Matter? � Matter is anything that has mass and takes up space.

What is Matter? � Matter is anything that has mass and takes up space. � All matter is made of particles. The type and arrangement of the particles determines the properties of the matter. � Most matter exists as solids, liquids, or gases.

Measuring Matter �Volume: the space an object takes up. Measured by: calculating L X

Measuring Matter �Volume: the space an object takes up. Measured by: calculating L X W X H, or in m. L with a Graduated Cylinder �Mass: the quantity of matter contained in an object. Measured by: Triple-beam Balance or Electronic Balance �Weight: the force produced by gravity acting on the mass of an object. Scientists express force in newtons, but they express mass in kilograms. Because gravity varies from place to place, weight can change but mass won’t.

Physical Properties � Physical Property= a characteristic of a substance that does not involve

Physical Properties � Physical Property= a characteristic of a substance that does not involve a chemical change. � These include: density, color, what state of matter it typically exists in, hardness, melting point or boiling point Whether water is ice or liquid, it is still water. Changing its state doesn’t change its’ identity. The sugar in the tea is still sugar, even if it is dissolved in the water of the tea.

Chemical Properties Tearing paper into pieces is a physical change—it is still paper. But,

Chemical Properties Tearing paper into pieces is a physical change—it is still paper. But, burning it changes its chemical composition. Burning paper turns it into a new substance. � Chemical Properties= a property of matter that describes a substance’s ability to participate in chemical reactions. � Chemical properties can only be determined by trying to cause a chemical change! If it changes to something else, that was a chemical change.

Evidence of Chemical Changes The Formation of a Precipitate The Release or Absorption of

Evidence of Chemical Changes The Formation of a Precipitate The Release or Absorption of Energy The Evolution of a Gas: the production of a gas is often observed by bubbling A Color Change in the Reaction System

Reactants vs. Products �In an equation, the substances on the left- hand side of

Reactants vs. Products �In an equation, the substances on the left- hand side of the arrow are the reactants. The substances on the right side are the products.

Important!!! �It is vital to understand that whether matter undergoes physical or chemical changes,

Important!!! �It is vital to understand that whether matter undergoes physical or chemical changes, matter is neither created, nor destroyed; it is only rearranged. �This is known as the Law of Conservation of Mass. Whatever matter you start with, you end with the same amount. This is a fundamental concept in chemistry and will be revisited many times.

Every Change in Matter Involves a Change in Energy � All physical and chemical

Every Change in Matter Involves a Change in Energy � All physical and chemical changes involve a change in energy. Energy is the ability to do work. � Sometimes, energy must be supplied for the change to occur. � Other times, energy is released. Both of these reactions involve Hydrogen and Oxygen—Water!

Energy v Temperature �It’s easy to get confused between the concept of energy (the

Energy v Temperature �It’s easy to get confused between the concept of energy (the ability to do work) and temperature (a measure of motion of the particles making up a substance). �It’s true that high-temperature objects possess a great deal of energy, but let’s look at a couple of examples.

Energy v Temperature �Ex. 1: A sample of a liquid substance is vaporized by

Energy v Temperature �Ex. 1: A sample of a liquid substance is vaporized by increasing its temperature. Before and after, the substance has a mass of 50 g. Which has more energy, the liquid or gas? �Answer; the gas. Since the mass has not changed, we can conclude that only the energy amount has changed.

Energy v Temperature �Ex. 2: A sample of water in a Styrofoam cup has

Energy v Temperature �Ex. 2: A sample of water in a Styrofoam cup has a mass of 50 g and a temperature of 100 degrees Celsius. Another sample of water in a large tub has a mass of 50, 000 g and a temperature of 50 degrees Celsius. Which has more energy? �Answer: The water in the tub. Since it has much more matter, more energy is distributed in it vs. the much smaller mass in the cup.

Changing States of Matter �Ice melting and water boiling are examples of physical changes.

Changing States of Matter �Ice melting and water boiling are examples of physical changes. �A physical change affects only the physical properties of a substance. When ice melts and turns into liquid water, you still have the same substance represented by the formula H 2 O. When water boils and turns into vapor, the vapor is still H 2 O. Only the physical state of the substance is changed. In contrast, the reaction of H and O to form http: //www. nsf. gov/news/special_reports/che H 2 O is a chemical change. mistrynow/chem_ice. jsp

Pure Substance/Elements �All matter is composed of about 110 different kinds of atoms. Atoms

Pure Substance/Elements �All matter is composed of about 110 different kinds of atoms. Atoms can be physically mixed or chemically combined to form all kinds of matter.

Pure Substances �A pure substance is a sample of matter (either a single element

Pure Substances �A pure substance is a sample of matter (either a single element or a single compound) that has definite chemical and physical properties. The helium atoms inside these balloons are an example of a pure substance. The copper wire inside these electrical cords is a pure substance.

Elements are Pure Substances �Elements are pure substances that contain only one kind of

Elements are Pure Substances �Elements are pure substances that contain only one kind of atom. �Copper and Helium are elements. �Each element has its own unique set of physical and chemical properties and is represented by a distinct chemical symbol.

Elements as Single Atoms or as Molecules �Some elements (such as Helium) exist as

Elements as Single Atoms or as Molecules �Some elements (such as Helium) exist as single atoms. �Other elements exist as molecules: Molecule= the smallest unit of a substance that keeps all of the physical and chemical properties of that substance; it can consist of one atom or two or more atoms bonded together.

Compounds �Pure substances that are not elements are called compounds. �Compounds are composed of

Compounds �Pure substances that are not elements are called compounds. �Compounds are composed of more than one kind of atom. �Compounds are represented by formulas, which show the ratio of the atoms. The molecular formula and structural diagram of Aspirin:

Mixtures �A sample of matter that contains two or more pure substances is a

Mixtures �A sample of matter that contains two or more pure substances is a mixture. �Most kinds of food are mixtures (except for sugar and salt). �Water is not a mixture of hydrogen and oxygen—they are bonded as a molecule, not just physically mixed. Also, the ratio of two hydrogen to 1 oxygen is the same in every molecule.

Mixtures can Vary in Composition and Properties �A glass of sweetened lemonade is a

Mixtures can Vary in Composition and Properties �A glass of sweetened lemonade is a mixture. If you have ever had a glass that is just too sweet or not sweet enough, you have experienced a characteristic of mixtures. �A mixture doesn’t always have the same balance of ingredients. Therefore, their properties can change.

Homogenous vs. Heterogeneous Mixtures � Homogenous Mixtures —describes a mixture that has a uniform

Homogenous vs. Heterogeneous Mixtures � Homogenous Mixtures —describes a mixture that has a uniform distribution of materials throughout. � Ex: sweetened tea or 14 karat gold � Heterogeneous Mixtures—is composed of components that are dissimilar (not alike, nor in equal quantities) � Ex: Sand water or a salad

Classification of Matter

Classification of Matter

Classification of Matter—Review Anything that has mass and takes up space All of the

Classification of Matter—Review Anything that has mass and takes up space All of the particles (atoms or molecules) in the sample are identical to each other Pure substances made of only one type of atom Molecule: A particle made of two or more atoms bonded together Pure substance made of more than one type of atom bonded together Mixture made of different types of particles that is uniformly distributed throughout. Contains two or more different types of particles (atoms or molecules) not bonded to each other Mixture that is made of different types of particles that do not have equal quantities

Review what you’ve learned: � Your friend mentions that she eats only natural foods

Review what you’ve learned: � Your friend mentions that she eats only natural foods because she wants her food to be free of chemicals. What is wrong with this reasoning? � Is toasting bread an example of a physical or chemical change? Why? � Classify each of the following as a physical change or a chemical change and provide evidence: � a. cracking an egg � b. using bleach to remove a stain from a shirt � c. burning a candle � d. melting butter in the sun