Understanding Density, Mass, and Volume

Density Definitions

• Density is the amount of matter in a space, calculated as mass divided by volume, typically measured in g/cm³, g/mL, etc.
• Mass refers to the quantity of matter within an object, often measured in grams, kilograms, milligrams, or pounds.
• Volume is the amount of space that an object occupies, measured in mL, L, cm³, or m³.

Units for Density, Volume, or Mass

• Kilogram (kg) is a unit of mass.
• Cubic centimeter (cm³) is a unit of volume.
• Gram per milliliter (g/mL) is a unit of density.
• Cubic meter (m³) is a unit of volume.
• Milliliter (mL) is a unit of volume.
• Gram (g) is a unit of mass.
• Kilogram per liter (kg/L) is a unit of density.
• Density is a physical property

Density Calculation Examples

• An object with a mass of 200 g and a volume of 50 cm³ has a density of 4 g/cm³.
• A gold bar with a density of 19 g/cm³ and a mass of 9500 g has a volume of 500 cm³.
• A piece of aluminum with a density of 2.6 g/cm³ and a volume of 15 cm³ has a mass of 39 g.
• A cricket ball with a density of 0.8 g/cm³ and a mass of 165 g has a volume of 206.25 cm³.
• A cube with a side length of 8 cm and a mass of 960 g has a density of 1.875 g/cm³.
• A cylinder with a mass of 128 g, a radius of 4 cm, and a height of 9 cm has a density of 0.28 g/cm³.
• An irregular object of 60.0 g is placed in a graduated cylinder; the water level rises from 75.0 mL to 90.5 mL, its density is 3.9 g/mL.

Density Concepts

• Ice floats on water because it is less dense; water is unique as its solid form is less dense than its liquid form.
• To determine an irregular object's density, measure its mass, find its volume by water displacement, and then calculate density by dividing mass by volume.
• If an object's mass remains constant but and its volume increases, its density decreases.
• A rock is denser than a sponge of the same volume because the rock contains more matter.

Density Formula

• The formula for calculating density is mass divided by volume.

Density Example

• An object with a mass of 50 g and a volume of 10 cm³ has a density of 5 g/cm³.

Material Density

• Gold is the most dense material listed.

Object Density & Water

• If an object sinks in water, its density is greater than water's density.

Substance Density & Temperature

• The density of a substance decreases when its temperature increases, assuming it expands.

Object Density & Cutting

• Cutting an object in half does not change its density; it remains the same.

Wood Density

• Wood floats on water due to its density being lower than that of water.

Liquid Density

• When combining two liquids of different densities, the denser liquid sinks below the less dense liquid.

Density Defined

• Density is mass divided by volume.

Object Density & Water

• Objects with a higher density than water sink.

Density & Volume

• Two objects with the same volume do not necessarily have the same density.

Temperature & Density

• An object's density can change if its temperature changes.

Units

• The unit g/cm³ is commonly used for solids.

Helium Density

• A balloon filled with helium rises because helium is less dense than air.

States of Matter & Density

• Gases are generally less dense than liquids.

Object Compression

• Compressing an object increases its density.

Density to Identify

• Density can help identify unknown substances.

Ice Density

• Ice is less dense than liquid water.

Matching Terms

• Water Displacement is a method for finding the volume of irregular objects.
• Volume is the amount of space an object occupies.
• Sink describes what an object does if it has greater density than the surrounding fluid.
• Density is mass divided by volume.
• Buoyancy is the ability of an object to float.
• Float describes what an object does if it has lower density than the surrounding fluid.
• Mass is the amount of matter in an object.

Sodium Atom

• A sodium atom has 11 protons, 12 neutrons, and 11 electrons

Periodic Table: Group vs. Period

• Groups are vertical columns, and periods are horizontal rows; the periodic table has 18 groups and 7 periods.

Noble Gases

• Noble gases do not easily react with other substances.

Metals vs. Nonmetals

• Metals are shiny, hard, malleable, ductile, and good conductors, while nonmetals are not shiny, are soft, not malleable or ductile, and are poor conductors.

Number of Neutrons

• The number of neutrons in an atom is determined by subtracting the atomic number from the atomic mass.

Elements Arrangement

• Elements are arranged by increasing atomic number to avoid discrepancies that arose when organized by atomic mass.

Periodic Table Pioneers

• Dmitri Mendeleev formulated the periodic table and arranged elements by atomic mass, predicting undiscovered elements.
• Henry Moseley discovered the atomic number as the number of protons in the nucleus.

Periodic Table Info

• Each box on the periodic table contains the element name, chemical symbol, and atomic mass.

Atomic Number

• The atomic number represents the number of protons in an element.

Chemical Symbol O

• The element with the chemical symbol "O" is Oxygen

Rows on Periodic Table

• The rows in the periodic table are called periods.

Same Group Elements

• Elements in the same group have similar properties.

Group 1 Reactive Metal

• Francium is the most reactive metal in Group 1.

Noble Gases Group

• Noble gases are in Group 18.

Atomic Mass

• The atomic mass of an element is determined by the number of protons and neutrons.

Carbon Electrons

• Carbon (C) has 6 electrons.

Metal Element

• Iron (Fe) is a metal.

Group 18 State

• Not all elements in Group 18 are gases at room temperature.

Period Properties

• Elements in the same period do not have the same number of electrons.

Table Arrangement

• The periodic table is arranged by increasing atomic number, not atomic mass.

Metal Placement

• Metals are found on the left side of the periodic table.

Halogens

• Halogens (Group 17) are highly reactive nonmetals.

Atomic Mass Whole Number

• The atomic mass is not always a whole number.

Electrons & Nucleus

• Electrons are not found in the nucleus of an atom.

Element Symbol

• An element's chemical symbol is always one or two letters.

Hydrogen Metal

• Hydrogen is not a metal.

Neutral Atom

• The number of protons equals the number of electrons in a neutral atom.

Matching - Group

• A vertical column on the periodic table.

Matching - Periodic Table

• A chart organizing all known elements.

Matching - Halogens

• Very reactive nonmetals.

Matching - Period

• A horizontal row on the periodic table.

Matching - Atomic Number

• Number of protons in an atom.

Matching - Noble Gases

• Group 18, known for being unreactive.

Matching - Atomic Mass

• Total number of protons and neutrons in an atom.

Matching - Alkali Metals

• Highly reactive metals