pssa prep chemistry

PSSA Science Prep Chemistry

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Opening Question: A scientist creates a reaction by mixing two chemicals in a beaker. As the reaction proceeds, water droplets condense and eventually freeze on the sides of the beaker. Is the reaction endothermic or exothermic? Waterfall at 3 after the hour…start typing!

Use characteristic physical or chemical properties to distinguish one substance from another (e.g., density, thermal expansion/contraction, freezing/melting points, streak test)

Today’s Objectives: ChemistryExplain the differences among elements, compounds, and mixtures.

Identify and describe reactants and products of simple chemical reactions.

Explain the Law of Conservation of Mass

Recognize that all matter consists of atoms

Compare the particle arrangement and type of particle motion associated with different states of matter

Identify the basic properties of acids and bases

• Elements- chemical element is a substance that cannot be broken down by chemical means. Elements are defined by the number of protons they possess.

• Compounds-A substance containing atoms of two or more elements that can be separated into elements through chemical reactions. Water is an example of a compound.

• Mixture-A combination of two or more substances that do not change chemically when mixed. Trail mix is an example of a mixture.* Homogenous Mixture-a mixture in which the ratio of each

component to the others is the same everywhere in the mixture (a.k.a. solution)

* Heterogeneous Mixture-a mixture in which different parts have different compositions, made of different proportions of particular atoms or molecules

Elements, Compounds, Mixtures

1) Vince is baking a cake. He pours flour and sugar into an empty bowl. The substance in the bowl is a(n) __________.

A.mixture B.compound C.element D.atom

PSSA Prep Questions

2) Sharon pours salt into a glass of water. The salt dissolves. The substance in the glass is a(n) __________.

A.mixture B.compound C.atom D.element

Answers on next slide….

1) Vince is baking a cake. He pours flour and sugar into an empty bowl. The substance in the bowl is a(n) __________.

A.mixture B.compound C.element D.atom

PSSA Prep Questions

2) Sharon pours salt into a glass of water. The salt dissolves. The substance in the glass is a(n) __________.

A.mixture B.compound C.atom D.element

3) Megan left her bicycle outside on the patio while she went on vacation for several weeks. When she returned, Megan discovered a reddish substance, rust, on the handlebars of her bicycle. The rust is an example of a(n) __________.

A.mixture B.atom C.compound D.element

PSSA Prep Questions

4) Which of the following statements is false?

A.Two or more different atoms combine chemically to form an element. B.Two or more different substances combine physically to form a mixture. C.Two or more atoms combine chemically to form a molecule. D.Two or more elements combine chemically to form a compound.


Question 5:A. element; compound; mixtureB. compound; compound; elementC. element; element; compoundD. compound; element; mixture

PSSA Prep Questions


• Law of Conservation of Mass is a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants.

• Matter cannot be created or destroyed in any ordinary chemical reaction.

• In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.

Law of Conservation of Mass

Question 6:A. atoms; atom; compoundB. compounds; atom; moleculeC. molecules; molecule; compoundD. atoms; molecule; compound


• Chemical Reactions-The process of breaking and forming bonds between elements. * Covalent Bonds-a bond in which electrons

are shared between the bonded atoms * Ionic Bonds-the force of attraction between

a charged atom (or group of connected atoms) and another with the opposite charge

• Reactant-the starting molecules in a chemical reaction

• Products-the molecules that result from a chemical reaction

Chemical Reactions

Ionic Compounds Covalent Compounds

Generally have high freezing and boiling points

Generally have low freezing and boiling points

Most are soluble in water

Many are insoluble in water

Generally are good electrical conductors when melted or dissolved in water

Generally are poor electrical conductors in all states

PSSA Prep Questions

7) In an octane molecule, carbon atoms share electrons with hydrogen atoms. Which of the following is most likely true of octane?

A. It has a low boiling pointB. It dissolves easily in waterC. It freezes at high temperaturesD. It is a good electrical conductor Answers on next slide….

Ionic Compounds Covalent Compounds

Generally have high freezing and boiling points

Generally have low freezing and boiling points

Most are soluble in water

Many are insoluble in water

Generally are good electrical conductors when melted or dissolved in water

Generally are poor electrical conductors in all states

PSSA Prep Questions

7) In an octane molecule, carbon atoms share electrons with hydrogen atoms. Which of the following is most likely true of octane?

A. It has a low boiling pointB. It dissolves easily in waterC. It freezes at high temperaturesD. It is a good electrical conductor

• Exothermic Reaction is a chemical reaction that releases energy in the form of light or heat.

• Endothermic Reaction a chemical reaction during which the system absorbs energy from its surroundings in the form of heat.

Chemical Reactions

Trial Initial Temperature

Final Temperature

1 27.5˚C 28.2˚C2 27.2˚C 26.1˚C3 27.9˚C 27.1˚C4 27.1˚C 25.8˚C

8) INITIAL AND FINAL TEMPERATURES IN CHEMICAL REACTIONSA scientist combines different substances and observes their reactions, as shown in the table. In which trial did an exothermic reaction most likely occur?

A. Trial 1B. Trial 2C. Trial 3D. Trial 4

W + X Y + Z

• 9) A scientist carries out this reaction several times in a sealed container with a fixed volume. The initial amounts of reactants and products are equal in each trial. In which of the following trials is the reaction rate lowest?

A. Trial 1: 0.31 mg of Y produced per minute

B. Trial 2: 0.47 mg of Y produced per minute

C. Trial 3: 0.31 mg of Y produced per second

D. Trial 4: 0.47 mg of Y produced per second.

PSSA Prep Question


• Atom-A tiny particle that is the fundamental building block of substances.

• Molecule-two or more atoms bonded together.* Proton-a positive (+) particle in the nucleus of an atom. The

number of protons in each atom is the atom’s atomic number.

* Neutron-a neutral particle with approximately the same mass as a proton, found in nuclei of atoms along with protons. The number of neutrons plus the number of protons equals the atom’s atomic mass.

* Electron-a negatively (-) charged particle with much less mass than protons and neutrons (approximately 1/2000), found around the nuclei of atoms

* Valance electron-the electron in the outermost shell of an atom and the electron that participates in chemical bonding.

All matter is made up of atoms.

10) A chlorine atom has 17 protons, 18 neutrons, and 17 electrons. What can you conclude about the overall charge of the atom?

A. It is neutral

B. It is positive

C. It is negative

D. It is undefined

11) The atomic number of neon is 10. What can you conclude about the structure of a neon atom?

A. It has ten protons

B. It has ten valence electrons

C. It has five protons and five neutrons

D. It has nine protons and one electron

PSSA Prep Questions


• Solid-something with a definite shape that is not easily changed

• Liquid- Something that flows freely and takes the shape of its container. We know water is a liquid because we can pour it, and it takes the shape of whatever container we put it in.

• Gas - matter with no definite shape, but that takes the shape of its container and fills it completely; usually invisible

The distance between particles determines the state of matter for a material. When a material changes state, the average spacing of its particles change.Solids: are always vibrating, packed very closely together, but they do not exchange positions.Liquids: also packed closely together but have enough energy to slip and slide past one another. Gases: are spread very far apart, in constant, rapid motion, bouncing off of walls and each other.

Solids, Liquids, and Gases

• Acids-a substance that is characterized by a sour taste and has a pH of less than 7

• Bases-a substance that has a bitter taste and a slippery feel, and a pH of greater than 7

• PH Scale-a scale that measures the acidity or baseness of a solution

12) An acidic solution could have a pH ofA. 7 B. 10 C. 3 D. 14

Acids and Bases


13) When a small piece of white marble rock is carefully placed in a beaker of hydrochloric acid, bubbles form on the surface of the rock and rise to the top of the liquid.

Which conclusion best fits this observation?

A.The rock reacted with the acid and made a new gaseous substance.

B.The rock was changed by the acid into its gaseous form.

C.The rock dissolved in the acid by breaking into its smallest pieces.

D.The rock heated the acid until it began to boil.


• Physical change-changes in matter that involve changes in the relationships among the molecules and/or in their motions, but not in the compounds or elements present* Physical properties-the properties of a

substance that can be observed without changing the chemical makeup of the substance

• Chemical Change-changes in matter that involve changes in the types of molecules present, in which bonds between atoms are broken and/or formed * Chemical Properties-properties of a

substance relating to the chemical nature and reactivity of the substance

Properties of Matter

Don’t try this at home….

14) All substances have characteristic properties. If one of these properties can be observed without changing the identity of the substance, it must be a

A.physical property. B.universal property. C.biological property. D.chemical property

PSSA Prep Questions

15) Water is a very unique substance because it can exist in all three phases of matter (solid, liquid, gas) within the normal temperature ranges found on Earth.When one observes the phase of matter of water, one observes a property of matter.

A.geological B.chemical C.biological D.physical


16) Adam is trying to identify a solid. He places a small amount of the substance in an acid solution and observes whether or not a reaction takes place. This test is based on a _______ property.

A.chemical B.biological C.radical D.physical

PSSA Prep Questions

17) Which of the following is a chemical property?

A.boiling point B.melting point C.density D.combustibility


The table below shows properties of the element gold (Au).

Property Gold'sCharacteristics

Color yellow

Density 19.32 g/mL

Electronegativity 2.54

Ionization Potential 9.225

Boiling Point 2807°C

Melting Point 1064.58°C

18) A physical property of gold is _________________________.

A.melting point of 1064.58°C B.density of 19.32 g/mL C.boiling point of 2807°C D.all of these


Scientific Method

While watching this clip: Fill up the chat box with what you idea of the word “hypothesis” is….

• Question

• Research/Observe

• Hypothesis

• Independent Variable

• Dependent Variable

• Conclusion

Match the term with its definition

• A statement that you can prove by conducting an experiment. Not always an “if-then”

• Ask yourself “What, Why, How…”• Independent Variable• The data variable, response to

independent variable• Begin to gather information to answer

your question. • Control• The variable being tested or

manipulated by the researcher. • The answer to your questions based on

the analyzed dataAnswers on next slide….

• Question

• Research/Observe

• Hypothesis

• Independent Variable

• Dependent Variable

• Conclusion

Match the term with its definition

• A statement that you can prove by conducting an experiment. Not always an “if-then”

• Ask yourself “What, Why, How…”• The data variable, response to

independent variable• Begin to gather information to

answer your question. • The variable being tested or

manipulated by the researcher. • The answer to your questions

based on the analyzed data

• A scientist studies the behavior of light emitted from a star to determine the chemical composition of the star. Which of the following best describes this activity?

A. Stating a hypothesisB. Asking a scientific questionC. Making a direct observationD. Making an indirect observation

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