Mass, Matter, Volume & Density
What scientific tool is used to measure the mass of an object?
What tool is used to measure the weight of an object?
A triple beam balance
A spring scale
They can be observed and measured without changing the identity of a substance.
(What are...?)
What are physical properties?
Give an example of a chemical change that causes a production of odor.
Milk souring or eggs rotting.
Matter can be classified into three major classes. What are they?
Elements, compounds, and mixtures
What is the atomic number of an element?
The number of protons in the nucleus of an element.
How is mass different from weight?
Mass and weight are related but not the same: mass is the amount of matter in an object and does not change regardless of location, while weight is the force of gravity pulling on that mass and depends on the strength of gravity where the object is. Mass is measured in kilograms or grams, while weight is measured in newtons. For example, a 20-kilogram suitcase has the same mass on Earth and the Moon, but it weighs much more on Earth because Earth’s gravity is stronger.
Give five examples of physical properties.
Density, Electrical Conductivity, Solubility, Luster, Boiling point, melting point, malleability
Which of the following is NOT a physical change?
Stretching a rubber band
Dissolving sugar in water
Cutting your hair
Silver jewelry tarnishing
Melting butter
Bending a paper clip
Silver jewelry tarnishing
What pH is classified as acidic? What pH is classified as neutral? What pH is classified as basic?
7 is neutral. Above 7 is basic. Below 7 is acidic
What elements make up living things?
Carbon, hydrogen, oxygen, nitrogen, phosphorus, and calcium
Find the volume of a box with the length of 11 cm, width of 8 cm, and height of 13 cm.
1144 cm^3.
What are the difference between physical and chemical properties?
A physical property can be observed without changing the identity of a substance. A chemical property is observed by changing the properties of a substance.
What is the law of conservation of energy? Give an example.
The law of conservation of energy states that energy cannot be created or destroyed; it can only change from one form to another or transfer between objects. The total amount of energy in a closed system always remains constant.
Example: When you drop a ball, its potential energy (stored energy due to height) is converted into kinetic energy (energy of motion) as it falls. Just before it hits the ground, almost all of the potential energy has transformed into kinetic energy, but the total amount of energy stays the same.
What is the difference between an organic compound and an inroganic compound?
Organic refers to compounds that contain carbon and hydrogen.
Describe metals.Where do they appear on the periodic table?
Metals are elements that are typically shiny, good conductors of heat and electricity, malleable (can be hammered into sheets), and ductile (can be drawn into wires). Most metals also tend to lose electrons in reactions, forming positive ions.
On the periodic table, metals appear on the left and center. This includes groups like the alkali metals, alkaline earth metals, transition metals, and some groups below them.
👉 The dividing line between metals and nonmetals is often shown as a “stair-step” line (starting near boron). Elements along that line are the metalloids.
A basalt rock displaces 16 mL of water. The density of the rock is 3.0 g/cm^3. What is the mass of the rock?
48 grams
What type of properties stay the same regardless of the amount of the sample? These properties are used to identify the sample.
Characteristic Properties
What is the law of conservation of mass? Give an example.
The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction; it can only change forms. This means that the total mass of the reactants (the starting substances) is always equal to the total mass of the products (the substances formed).
Example: When water (H₂O) is formed by combining hydrogen gas (H₂) and oxygen gas (O₂), the total mass of the hydrogen and oxygen used is exactly equal to the mass of the water produced. If you start with 2 grams of hydrogen and 16 grams of oxygen, you’ll end up with 18 grams of water.
What is the difference between homogeneous mixtures and heterogeneous mixtures? Give an example of each one.
A homogeneous mixture is a mixture in which the components are evenly distributed, and you cannot see the different parts because they look uniform throughout.
Example: Salt dissolved in water — the salt particles are spread out evenly, making the mixture look the same everywhere.
A heterogeneous mixture is a mixture in which the components are not evenly distributed, and you can often see the different parts.
Example: A salad with lettuce, tomatoes, and cucumbers — you can see and pick out the different ingredients.
What are the three parts of an atom and what are their charges?
Protons are positive, neutrons are neutral, and electrons are negative
An object has a density of 1.5 g/cm³ and a volume of 20 cm³. What is its mass?
30 grams
A sample of gold has a mass of 579 grams. The volume of the sample is 30 cm^3. What is density of the gold sample?
19.3 g/cm^3
What are the five indicators of a chemical change? How can you tell a chemical change has happened? (Name at least three for credit)
Production of an odor
Production of a gas
Formation of a precipitate
Change in energy
Change in color
What is a suspension? What is a colloid? Give an example of each one.
A suspension is a type of mixture in which solid particles are large enough that they do not dissolve and will eventually settle out if left undisturbed.
Example: Sand in water — the sand particles will sink to the bottom over time.
A colloid is a mixture where very small particles are evenly spread throughout another substance, and they do not settle out, but they can scatter light (this is called the Tyndall effect).
Example: Milk — tiny fat droplets are dispersed in water and stay mixed without settling.
What elements make up Earth? (Name at least 3)
Oxygen, silicon, aluminum, calcium, sodium, potassium, magnesium, nickel, and iron