Science Notes 12/3/24

Matter – anything that has mass and takes up space.

Substance – A single kind of matter that is pure and has a specific set of properties.

Physical property- A characteristic of a pure substance that can be observed without changing it

into another substance.

Chemical property – A characteristic of a substance that describes its ability to be changed into

another substance.

Atom – the basic particle from which all substances are made; the smallest particle of an

element that has the properties of that element.

Element – a pure substance that cannot be broken down into other substances by chemical or

physical means.

Molecule – a neutral group of two or more atoms held together by covalent bonds.

Compound – A substance made by two or more elements chemically combined in a specific

ratio or proportion.

Mixture –two or more substances that are together in the same place but whose atoms are not

chemically bonded.

Mass- a measure of the amount of matter in an object.

Volume – the amount of space that matter occupies.

Weight – a measure of the force of gravity acting on an object.

Density – the measurement of how much mass of a substance is contained in a given volume.

Physical change – a change that alters the form or appearance of a material but does not make

the material into another substance.

Chemical change – a change in which one or more substances combine or break apart to form

new substances.

Concepts

p. 109 What is the difference between a pure substance and an impure substance, for example

table salt versus sea salt?

A pure substance has the same chemical composition whether you are looking at a little bit or a

lot. An impure substance is one in which you can find at least a small amount of other

substances mixed with it.

p. 110 What are some examples of physical properties of a substance? Color, melting point,

boiling point, size, texture, etc.

p. 111 What are some examples of chemical properties of a substance? flammability, reactivity.

p. 114. What do the subscript numbers in the formula for a compound stand for? For example,

the 2 in the formula in CO2? What does mean if there is no number after the chemical symbol?

The subscripts tell you the number of atoms of each element in the formula, for example 2

oxygen atoms in CO2. If there is no number, then that means there is only one atom of the

element in the formula.

p. 115 What is the difference between a homogeneous and a heterogeneous mixture? Give

examples of each.

Mixtures that are homogeneous cannot be easily separated into their parts (milk, soda,

chocolate). Mixtures that are heterogeneous can be separated (trail mix, fruit salad)

p. 115 What are some ways that mixtures can be separated into its parts? Filtration, distillation,

sieving, by magnetic properties, evaporation

p. 120 How does the weight of an object depend on the force of gravity acting upon it?

The higher the force of gravity the greater the weight will be.

p. 122 How is density calculated and what are the units?

Density = mass/volume g/ml or g/cm3

p. 123 In general, what happens to the density of most substances when you increase their

temperature?

As you increase temperature the particles move further apart and the density of the substance

decreases.

p. 129-130 What are some examples of physical changes in matter?

A change in size, shape, or state of matter

p. 131 -132 What are some examples of chemical changes in matter?

A substance undergoes a chemical reaction or reacts with another substance to become one or

more new substances.

p. 132 What is the Law of Conservation of Mass?

In a chemical reaction, matter is not created or destroyed, it only changes form.

Topic 4 – Solids, Liquids and Gases

Vocabulary

Solid – Matter with a definite shape and volume.

Liquid –Matter with no definite shape but a definite volume.

Viscosity – a resistance of a liquid to flowing.

Surface Tension – an inward force, or pull, among molecules in a liquid that brings the

molecules on the surface closer together.

Gas -matter with no definite shape or definite volume.

Thermal energy – the total kinetic and potential energy of all the particles in a substance.

Temperature – the average kinetic energy of the particles in a substance.

Melting point – the temperature at which a solid changes to a liquid, it is the same as the

freezing point in which a liquid becomes a solid.

Freezing point – the temperature at which a liquid becomes a solid. It is the same as the melting

point in which a solid becomes a liquid.

Vaporization – the chance of state from liquid to a gas.

Boiling point – the temperature at which a liquid boils.

Evaporation – the process by which molecules at the surface of a liquid absorb enough energy

to change into a gas.

Condensation – the change in state from gas to a liquid.

Sublimation – the change in state from a solid directly to a gas without passing through the

liquid state.

Pressure – the force pushing on a surface divided by the area of that surface.

Charles’s Law – A principle that describes the relationship between the temperature and volume

of a gas at constant pressure.

Boyle’s Law – a principle that describes the relationship between the pressure and volume of a

gas at constant temperature.

Concepts

p. 152 – What is the arrangement of particles in a solid and what is their movement?

The particles in a solid are densely packed. They vibrate in place.

p. 153 - What are the physical properties of a solid? Shape, structure, texture, color.

p. 154 What is the difference between a crystalline and an amorphous solid? Give example of

each type.

In a crystalline solid, the particles are arranged in a specific repeating pattern. Salt is an

example. An amorphous solid has a random arrangement of particles.

p. 155 – What is the arrangement of particles in a liquid and what is their movement? They are

densely packed but can slide past each other.

p. 155 - What are the physical properties of a liquid? Surface tension and viscosity

157 – What is the arrangement of particles in a gas and what is their movement?

They are not densely packed and move freely.

p. 157 - What are the physical properties of a gas? Gases can be expanded or compressed, and

they flow easily.

p. 161 – How are thermal energy and temperature related?

Increasing the thermal energy of a substance increases the movement of its particles and

increases its temperature.

p. 162 – What occurs while a substance is melting? The thermal energy of the particles

increases, and they vibrate fast enough to break free from their fixed positions.

p. 162 - Why doesn’t the temperature of a substance change while it is melting?

Because the thermal energy that is added to the substance is used to break the particles free

from their fixed position.

p. 163 – What happens when a substance is freezing?

The particles in a substance slow down and take on a fixed position.

p. 163 - Why doesn’t the temperature of a substance change when it is freezing?

Energy is being released from the substance as it freezes, and this prevents the temperature from

getting cooler.

p. 164 – What are the two ways vaporization can occur? How are they different?

Evaporation occurs at the surface of a liquid. Boiling occurs when the liquid reaches a specific

temperature and occurs through the liquid.

p. 165 – What is the effect of air pressure on the boiling point of a substance? Increasing the

pressure will cause the boiling point to increase. Decreasing the pressure will lower the boiling

point.

p. 174 – Explain how Charles’s Law is an example of a directly proportional relationship.

When the temperature of a gas increases, its volume increases. When the temperature of a gas

decreases, its volume decreases.

p. 177 – Explain how Boyle’s Law is an example of an inversely proportional relationship.

When the volume increases, the pressure decreases and when the volume decreases, the

pressure increases.

Topic 5 – Atoms and the Periodic Table

Lesson 1 and 2 Vocabulary and Concepts

Atom – the basic particle from which all substances are made; the smallest particle of an

element that has the properties of that element.

Electron –a tiny, negatively charged particles that moves around the outside of the nucleus of an

atom.

Nucleus –the central core of an atom that contains protons and neutrons.

Proton – a small, positively charged particle that is found in the nucleus of an atom.

Neutron – a small particle in the nucleus of an atom with no electrical charge.

Atomic Number –the number of protons in the nucleus of an atom.

Isotope – an atom with the same number of protons and a different number of neutrons from

other atoms of the same element.

Mass number – the sum of the protons and neutrons in the nucleus of an atom.

Concepts

p. 200 What is the modern model of an atom?

the nucleus is composed of protons and neutrons and the electrons travel around the nucleus in a

cloud-like region. Most the atom is empty space.

p. 202 What is the same and different about isotopes of the same element?

Same number of protons, different number of neutrons.

Lessons 3 and 4 Vocabulary and concepts

Chemically stable – an atom is chemically stable when its outer energy level is complete (8

electrons for energy levels 2 and higher.)

Chemical bond – the force that holds atoms together in a compound.

Ion – a charged particle that has either more or fewer electrons than protons.

Cation – a positively charged ion formed when an atom loses electrons.

Anion – a negatively charged ion formed when an atom gains electrons

Ionic bond – the force of attraction between the opposite charges of the ions in an ionic

compound.

Molecule – a neutral particle that forms as a result of electron sharing.

Covalent bond – a chemical bond formed through the sharing of electrons by atoms.

Understand how an atom becomes chemically stable.

- Gains or loses electrons in an ionic bond.

- Shares electrons with another atom in a covalent bond.

Understand covalent and ionic bonds and how each type of bond forms.

Ionic bonds form between metals and non-metals. The metal loses one or more electrons and

becomes positively charged. The non-metal gains electrons and becomes negatively charged.

Then the positively and negatively charged atoms attract each other and form a bond. Salt is an

example.

Covalent bonds form when two non-metals share electrons.