CHEM Topic 2 Lecture
Classification of Matter
Matter is anything that has mass and volume. It exists in different states: solid, liquid, and gas. A fourth state, plasma, also exists.
States of Matter
Solid:
Atoms have a repeating geometric structure.
Atoms vibrate in place.
Most dense state (except for water).
Crystalline pattern.
Atoms are still moving unless they're at absolute zero (-273 degrees Celsius).
Amorphous solids, like plastics, exist.
Liquid:
Atoms can slip past one another.
Takes on the shape of its container but has a fixed volume.
Atoms are attracted enough to each other that they don't break free.
Water is an exception, as it is most dense as a liquid, and ice floats because it's less dense.
Gas:
Atoms overcome attractive forces and spread as far apart as possible.
Have no attraction for one another, so they fly off in different directions.
The mass of a gas is much less than in solid or liquid states.
Changes in State
Sublimation: Solid changes directly into a gas (e.g., dry ice, iodine )
Deposition: Gas changes directly into a solid (e.g., frost/snow).
Heating Curve
Imagine taking ice and putting it on a hot plate. As heat is added:
The ice melts (fusion).
The water boils.
Kinetic energy increases with added heat, potentially leading to a gaseous state.
Temperature remains constant during phase changes (melting or boiling).
Different substances require different temperatures for these changes. Understanding the specific heat capacities of these substances can aid in predicting the temperatures at which they will change phases.
Sublimation Example
Pure iodine is a purple crystal.
Under the right conditions, almost any molecule can be forced to sublimate.
Skipping the liquid phase is a common feature of sublimation.
Heat is added to the material during sublimation.
Deposition Example
Water clouds are liquid water droplets in the atmosphere.
Classification of Matter
Pure Substances: Cannot be separated by physical means.
Elements: Composed of identical atoms (e.g., aluminum, oxygen, carbon). Represented on the periodic table.
Compounds: Composed of two or more different atoms chemically bonded in the same proportions (e.g., water (H2O), ammonia (NH3). Can only be separated by chemical reactions.
Mixtures: Two or more elements/compounds physically combined and can be separated by physical means.
Heterogeneous mixtures: Different components can be visually differentiated and separated by filtration (e.g., orange juice with pulp). You can typically see more than one thing present just by looking at it.
Homogeneous mixtures: Uniform throughout and separated by methods like boiling (e.g., saltwater, Kool-Aid). Have the same consistency throughout.
Key Concepts
Element: One kind of atom; the name of a kind of atom.
Compound: Always has the same proportions.
Decomposition: To separate hydrogen from oxygen in a water molecule requires a chemical reaction.
Brinklehoffs
Elements that always travel in pairs:
Bromine (Br_2)
Iodine (I_2)
Nitrogen (N_2)
Chlorine (Cl_2)
Hydrogen (H_2)
Oxygen (O_2)
Fluorine (F_2)
These are not considered compounds.
Abundance of Elements
A lot of hydrogen and oxygen in the US because of water.
A large amount of oxygen in the earth's crust because a lot of minerals have oxygen chemically bonded in them.
Separating Matter
Different methods:
Filtration
Distillation
Chemical reaction (Decomposition)
Examples of Classification
Helium: Element
Whole milk: Heterogeneous mixture (separate with a centrifuge)
Air: Homogeneous mixture (solution)
Sugar (sucrose): Compound
Propane: Compound
Iron: Element
Steel: Homogeneous mixture (mixture of iron and carbon)
Blood: Heterogeneous mixture (has different components that can be centrifuged out)
Physical and Chemical Properties
Physical properties: Properties unrelated to chemical reactions (e.g., density, color, boiling point, physical states).
Chemical properties: How a substance chemically reacts with other substances (e.g., flammability, oxidation).
Examples
Boiling and melting are physical changes (altering the state of the material).
Burning something is a chemical change (converting organic material into carbon dioxide and water vapor).
Classification of Matter
Matter is anything that has mass and volume. It exists in different states: solid, liquid, and gas. A fourth state, plasma, also exists. Think of it like this: matter is the "stuff" around you, whether it's the chair you're sitting on, the water you drink, or the air you breathe!
States of Matter
Solid:
Imagine atoms packed tightly together in a repeating geometric pattern. They're like little soldiers standing in formation.
Atoms vibrate in place; they don't move around.
Usually the most dense state (meaning it packs the most "stuff" into a space) – except for water, which is weird!
Crystalline pattern (think of salt or sugar crystals).
Atoms are still jiggling unless they're at absolute zero (-273 degrees Celsius), which is super cold!
Amorphous solids, like plastics, don't have a crystal structure.
Liquid:
Atoms can slip and slide past one another like marbles in a bag.
Liquids take the shape of their container but have a fixed volume. Pour water into a glass, and it fills the glass, but it's still the same amount of water.
Atoms are attracted enough to each other that they don't break free.
Water is special: it's most dense as a liquid. Ice floats because it's less dense.
Gas:
Atoms are like tiny explorers who have overcome attractive forces and spread out as far as possible.
Gases have no strong attraction for one another.
The mass of a gas is much less than the mass of the same substance in solid or liquid form.
Changes in State
Sublimation: Solid turns directly into a gas. Think of dry ice (CO2) disappearing in front of your eyes or iodine (I2) crystals releasing a purple vapor.
Deposition: Gas turns directly into a solid, like frost or snow forming on a cold day.
Heating Curve
Imagine putting ice on a stove. What happens?
The ice melts (fusion).
The water boils.
Kinetic energy (the energy of motion) increases with added heat.
Temperature stays still during phase changes (melting or boiling), like the water's taking a break at 100 degrees celsius while it is boiling.
Different substances change at different temperatures.
H2O(s) \rightarrow H2O(g)
Sublimation Example
Pure iodine is a cool purple crystal.
Almost any molecule can sublimate if conditions are right.
Skipping the liquid phase is normal during sublimation.
Heat is added during sublimation.
Deposition Example
Water clouds are actually liquid droplets.
Classification of Matter
Pure Substances: Cannot be separated by physical means.
Elements: Contain identical atoms (e.g., aluminum, oxygen, carbon). You can find them on the periodic table.
Compounds: Contain two or more different atoms chemically bonded in fixed proportions (e.g., water (H2O), ammonia (NH3)).
Mixtures: Have two or more elements/compounds physically combined, and can be separated by physical means.
Heterogeneous mixtures: Different parts appear clearly (e.g., orange juice with pulp).
Homogeneous mixtures: Uniform throughout (e.g., saltwater, Kool-Aid).
Key Concepts
Element: One kind of atom; the element's name is the name of the kind of atom the element is comprised of.
Compound: Always has the same element proportions.
Decomposition: Is needed to separate hydrogen from oxygen.
Brinklehoffs
Elements that always travel in pairs. Remember "Brinklehoffs are diatomic":
Bromine (Br_2)
Iodine (I_2)
Nitrogen (N_2)
Chlorine (Cl_2)
Hydrogen (H_2)
Oxygen (O_2)
Fluorine (F_2)
These are not compounds; they're just elements sticking together!
Abundance of Elements
A lot of hydrogen and oxygen in the US because of water.
Oxygen in Earth's crust is abundant because it is chemically bonded to minerals.
Separating Matter
Different methods:
Filtration
Distillation
Chemical reaction (Decomposition)
Examples of Classification
Helium: Element
Whole milk: Heterogeneous mixture (separate with a centrifuge)
Air: Homogeneous mixture (solution)
Sugar (sucrose): Compound (C{12}H{22}O_{11})
Propane: Compound
Iron: Element
Steel: Homogeneous mixture (mixture of iron and carbon)
Blood: Heterogeneous mixture (separate using a centrifuge)
Physical and Chemical Properties
Physical properties: Properties unrelated to chemical reactions (e.g., density, color, boiling point, physical states).
Chemical properties: How a substance reacts (e.g., flammability, oxidation).
Examples
Boiling and melting are physical changes (altering the state of the material).
Burning something is a chemical change (converting organic material into carbon dioxide and water vapor).
Classification of Matter
Matter is anything that has mass and volume. It exists in different states: solid, liquid, and gas. A fourth state, plasma, also exists. Think of it like this: matter is the "stuff" around you, whether it's the chair you're sitting on, the water you drink, or the air you breathe!
States of Matter
Solid:
Imagine atoms packed tightly together in a repeating geometric pattern. They're like little soldiers standing in formation.
Atoms vibrate in place; they don't move around.
Usually the most dense state (meaning it packs the most "stuff" into a space) – except for water, which is weird!
Crystalline pattern (think of salt or sugar crystals).
Atoms are still jiggling unless they're at absolute zero (-273 degrees Celsius), which is super cold!
Amorphous solids, like plastics, don't have a crystal structure.
Liquid:
Atoms can slip and slide past one another like marbles in a bag.
Liquids take the shape of their container but have a fixed volume. Pour water into a glass, and it fills the glass, but it's still the same amount of water.
Atoms are attracted enough to each other that they don't break free.
Water is special: it's most dense as a liquid. Ice floats because it's less dense.
Gas:
Atoms are like tiny explorers who have overcome attractive forces and spread out as far as possible.
Gases have no strong attraction for one another.
The mass of a gas is much less than the mass of the same substance in solid or liquid form.
Changes in State
Sublimation: Solid turns directly into a gas. Think of dry ice (CO2) disappearing in front of your eyes or iodine (I2) crystals releasing a purple vapor.
Deposition: Gas turns directly into a solid, like frost or snow forming on a cold day.
Heating Curve
Imagine putting ice on a stove. What happens?
The ice melts (fusion).
The water boils.
Kinetic energy (the energy of motion) increases with added heat.
Temperature stays still during phase changes (melting or boiling), like the water's taking a break at 100 degrees celsius while it is boiling.
Different substances change at different temperatures.
H2O(s) \rightarrow H2O(g)
Sublimation Example
Pure iodine is a cool purple crystal.
Almost any molecule can sublimate if conditions are right.
Skipping the liquid phase is normal during sublimation.
Heat is added during sublimation.
Deposition Example
Water clouds are actually liquid droplets.
Classification of Matter
Pure Substances: Cannot be separated by physical means.
Elements: Contain identical atoms (e.g., aluminum, oxygen, carbon). You can find them on the periodic table.
Compounds: Contain two or more different atoms chemically bonded in fixed proportions (e.g., water (H2O), ammonia (NH3)).
Mixtures: Have two or more elements/compounds physically combined, and can be separated by physical means.
Heterogeneous mixtures: Different parts appear clearly (e.g., orange juice with pulp).
Homogeneous mixtures: Uniform throughout (e.g., saltwater, Kool-Aid).
Key Concepts
Element: One kind of atom; the element's name is the name of the kind of atom the element is comprised of.
Compound: Always has the same element proportions.
Decomposition: Is needed to separate hydrogen from oxygen.
Brinklehoffs
Elements that always travel in pairs. Remember "Brinklehoffs are diatomic":
Bromine (Br_2)
Iodine (I_2)
Nitrogen (N_2)
Chlorine (Cl_2)
Hydrogen (H_2)
Oxygen (O_2)
Fluorine (F_2)
These are not compounds; they're just elements sticking together!
Abundance of Elements
A lot of hydrogen and oxygen in the US because of water.
Oxygen in Earth's crust is abundant because it is chemically bonded to minerals.
Separating Matter
Different methods:
Filtration
Distillation
Chemical reaction (Decomposition)
Examples of Classification
Helium: Element
Whole milk: Heterogeneous mixture (separate with a centrifuge)
Air: Homogeneous mixture (solution)
Sugar (sucrose): Compound (C{12}H{22}O_{11})
Propane: Compound
Iron: Element
Steel: Homogeneous mixture (mixture of iron and carbon)
Blood: Heterogeneous mixture (separate using a centrifuge)
Physical and Chemical Properties
Physical properties: Properties unrelated to chemical reactions (e.g., density, color, boiling point, physical states).
Chemical properties: How a substance reacts (e.g., flammability, oxidation).
Examples
Boiling and melting are physical changes (altering the state of the material).
Burning something is a chemical change (converting organic material into carbon dioxide and water vapor).
Classification of Matter
Matter is anything that has mass and volume. It exists in different states: solid, liquid, and gas. A fourth state, plasma, also exists. Think of it like this: matter is the "stuff" around you, whether it's the chair you're sitting on, the water you drink, or the air you breathe!
States of Matter
Solid:
Imagine atoms packed tightly together in a repeating geometric pattern. They're like little soldiers standing in formation.
Atoms vibrate in place; they don't move around.
Usually the most dense state (meaning it packs the most "stuff" into a space) – except for water, which is weird!
Crystalline pattern (think of salt or sugar crystals).
Atoms are still jiggling unless they're at absolute zero (-273 degrees Celsius), which is super cold!
Amorphous solids, like plastics, don't have a crystal structure.
Liquid:
Atoms can slip and slide past one another like marbles in a bag.
Liquids take the shape of their container but have a fixed volume. Pour water into a glass, and it fills the glass, but it's still the same amount of water.
Atoms are attracted enough to each other that they don't break free.
Water is special: it's most dense as a liquid. Ice floats because it's less dense.
Gas:
Atoms are like tiny explorers who have overcome attractive forces and spread out as far as possible.
Gases have no strong attraction for one another.
The mass of a gas is much less than the mass of the same substance in solid or liquid form.
Changes in State
Sublimation: Solid turns directly into a gas. Think of dry ice.
Deposition: Gas turns directly into a solid, like frost or snow forming on a cold day.
Heating Curve
Imagine putting ice on a stove. What happens?
The ice melts (fusion).
The water boils.
Kinetic energy (the energy of motion) increases with added heat.
Temperature stays still during phase changes (melting or boiling), like the water's taking a break at 100 degrees celsius while it is boiling.
Different substances change at different temperatures.
Sublimation Example
Pure iodine is a cool purple crystal.
Almost any molecule can sublimate if conditions are right.
Skipping the liquid phase is normal during sublimation.
Heat is added during sublimation.
Deposition Example
Water clouds are actually liquid droplets.
Classification of Matter
Pure Substances: Cannot be separated by physical means.
Elements: Contain identical atoms (e.g., aluminum, oxygen, carbon). You can find them on the periodic table.
Compounds: Contain two or more different atoms chemically bonded in fixed proportions (e.g., water (H2O), ammonia ( NH3).
Mixtures: Have two or more elements/compounds physically combined, and can be separated by physical means.
Heterogeneous mixtures: Different parts appear clearly (e.g., orange juice with pulp).
Homogeneous mixtures: Uniform throughout (e.g., saltwater, Kool-Aid).
Key Concepts
Element: One kind of atom; the element's name is the name of the kind of atom the element is comprised of.
Compound: Always has the same element proportions.
Decomposition: Is needed to separate hydrogen from oxygen.
Brinklehoffs
Elements that always travel in pairs. Remember "Brinklehoffs are diatomic":
Bromine (Br_2)
Iodine (I_2)
Nitrogen (N_2)
Chlorine (Cl_2)
Hydrogen (H_2)
Oxygen (O_2)
Fluorine (F_2)
These are not compounds; they're just elements sticking together!
Abundance of Elements
A lot of hydrogen and oxygen in the US because of water.
Oxygen in Earth's crust is abundant because it is chemically bonded to minerals.
Separating Matter
Different methods:
Filtration
Distillation
Chemical reaction (Decomposition)
Examples of Classification
Helium: Element
Whole milk: Heterogeneous mixture (separate with a centrifuge)
Air: Homogeneous mixture (solution)
Sugar (sucrose): Compound
Propane: Compound
Iron: Element
Steel: Homogeneous mixture (mixture of iron and carbon)
Blood: Heterogeneous mixture (separate using a centrifuge)
Physical and Chemical Properties
Physical properties: Properties unrelated to chemical reactions (e.g., density, color, boiling point, physical states).
Chemical properties: How a substance reacts (e.g., flammability, oxidation).
Examples
Boiling and melting are physical changes (altering the state of the material).
Burning something is a chemical change (converting organic material into carbon dioxide and water vapor).