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STANDARD 3a. Students know the structure of the atom and know it is composed of protons, neutrons, and electrons. Structure of Matter. All matter is made up of small particles called atoms An atom is the smallest unit of an element Composed of three particles - PowerPoint PPT Presentation
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STANDARD 3a
• Students know the structure of the atom and know it is composed of protons, neutrons, and electrons
Structure of Matter• All matter is made up of small
particles called atoms• An atom is the smallest unit of an
element• Composed of three particles
– Protons – positively charged particles in the nucleus (center)
– Neutrons – particles with no charge located in the nucleus
– Electrons – negatively charged particles surrounding the nucleus in shells also known as energy levels
• Most of the atom’s mass is located in the nucleus
Structure of Matter
18. Which of the following best describes an atom?
A Protons and electrons grouped together in a random pattern
B Protons and electrons grouped together in an alternating pattern
C A core of protons and neutrons surrounded by electrons
D A core of electrons and neutrons surrounded by protons
ANSWER: C
Structure of Matter
20. The diagram above shows models of two different atoms. Which subatomic particles are represented by the black dots?A protonsB neutronsC electronsD nuclei
ANSWER: C
Structure of Matter
22. Which particles in an atom account for nearly all the atom’s mass
A electrons only
B protons only
C neutrons only
D protons and neutrons
ANSWER: D
STANDARD 3b
• Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements
COMPOUNDS• All matter is made of elements• In nature, most elements are found
combined with other elements because most atoms are unstable
• When atoms combine, they form a chemical bond, which is a force of attraction between two atoms
• A compound is a substance made of two or more elements chemically combined in a set ratio. Water molecule is always made up of two hydrogen atoms to one oxygen atom.
COMPOUNDS• Valence electrons are the electrons that have
the highest energy level and are held most loosely because they are farthest away from the nucleus
• Atoms become stable (or happy) when they have a total of 8 valence electrons. All atoms except the noble gas atoms have fewer than 8 valence electrons
• Atoms achieve 8 valence electrons by bonding with other atoms
• Two main types of chemical bonds: ionic bonds and covalent bonds
• An ion is an atom or group of atoms that has an electric charge: positive or negative
COMPOUNDS
• Ionic Bond: a chemical bond that forms as a result of the attraction between positive and negative ions
• Covalent Bond: a chemical bond that forms when two atoms share valence electrons
• A molecule is a neutral group of two or more atoms joined by covalent bonds
• Water is a molecular compound with a chemical formula of H2O
COMPOUNDS24. Which of the following chemical
formulas represents a compound?
A He
B O2
C HCl
D Sn
ANSWER: C
COMPOUNDS
26. The atoms in a molecule of water are joined by
A ionic bonds
B covalent bonds
C unshared electrons
D shared protons
ANSWER: B
COMPOUNDS27. Magnesium reacts with oxygen to form
MgO. Properties of MgO are most likely
A similar to magnesium
B similar to oxygen
C different from magnesium or oxygen
D similar to both magnesium and oxygen
ANSWER: C
STANDARD 3c
• Students know atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers
STRUCTURE OF COMPOUNDS
• Ionic compounds form solids by building up repeating patterns of ions.
• The result is a solid with an orderly, three dimensional arrangement called a crystal
• Solid ionic compounds are hard and brittle, have high melting points and when melted or dissolved conduct electricity
STRUCTURE OF COMPOUNDS• Molecular compounds contain atoms
that are covalently bonded, forming molecules
• Molecular compounds have low melting and boiling points and do not conduct electricity
STRUCTURE OF COMPOUNDS• Some molecular compounds are
composed of polymers• A polymer is a very large molecule
made of a chain of many repeating, smaller molecules bonded together
• Many of the molecules that make up living things are polymers: proteins, DNA, carbohydrates
Amino acid NucleotideGlucose
STRUCTURE OF COMPOUNDS
28. Which is not a characteristic of a molecular compound?
A low melting point
B does not conduct electric current
C low boiling point
D hard, brittle solids at room temperature
ANSWER: D
STRUCTURE OF COMPOUNDS
29. What type of structure is shown in the diagram?
A atom
B crystal
C molecule
D polymer
ANSWER: B
STRUCTURE OF COMPOUNDS
30. Which of the following kinds of force helps hold the particles together?A electrical attractionB magnetic attractionC gravitational attractionD thermonuclear attraction
ANSWER: A
STRUCTURE OF COMPOUNDS
31. Some compounds found in the human body are long chains of smaller molecules. These chains are called
A carbon molecules
B covalent bonds
C polymers
D crystals
STANDARD 3d
• Students know the states of matter (solid, liquid, gas) depend on molecular motion
Molecular Motion32. Which type of
motion best represents the movement of gas particles?A Motion 1B Motion 2C Motion 3D Motion 4
ANSWER: A
STANDARD 3e• Students know that in solids the
atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently
Molecular Motion• Solid LiquidLiquid GasGas
Molecular Motion• Definite shape and volume• Lowest energy• Tightly packed together• Does not take the shape of its
container Definite volume but no definite shapeDefinite volume but no definite shape Slightly higher energy than solidsSlightly higher energy than solids Molecules slide past one anotherMolecules slide past one another Takes the shape of its containerTakes the shape of its container
No definite shape or volumeNo definite shape or volume Highest energyHighest energy Molecules move throughout the Molecules move throughout the
containercontainer Takes shape of containerTakes shape of container
SOLID
LIQUID
GAS
CHANGES OF STATE
• A change of state is the conversion of a substance from one physical form to another.
• All changes of state are physical changes.
• During a change of state, energy of a substance changes. Energy is either released or absorbed
CHANGES OF STATE
• Melting – from a solid to a liquid
• Freezing – from a liquid to a solid
• Vaporization – from a liquid to a gas– Boiling – takes place throughout the liquid– Evaporation – takes place only on the
surface
• Condensation – from a gas to a liquid
• Sublimation – from a solid to a gas
CHANGES OF STATE
CHANGES OF STATE
33. What occurs when liquid water becomes ice?A Energy is added to the water, so its
molecules move more slowlyB Energy is added to the water, so its
molecules move more quicklyC Energy is removed from the water,
so its molecules lock into placeD Energy is removed from the water,
so its molecules move apart
ANSWER: C
Changes of State34. The graph shows the effect of adding energy to water at
sea level. When the temperature reaches 100 degrees Celsius, what happens to the water molecules as energy continues to be added?A. The water molecules gain energy as the temperature continues to riseB The water molecules gain no energy and the temperature stays the sameC The water molecules become more ordered as the state changes to a gasD The water molecules move farther apart as the state changes to a gas
ANSWER: DANSWER: D
CHANGES OF STATE35. The diagram illustrates the particles of
a solid substance held in a container. What would happen if the substance gained enough energy so that it melted completely?A The particles would remain locked together in the same shapeB The particles would spread out
into a layer that fills the bottom part of the container
C The particles would spread apart widely and fill the entire containerD The particles would chemically
change into new substances
ANSWER: B
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