Unit 3: Properties of Matter
Reading:
BJU Chemistry: Ch. 2 "Matter"
AP Chem: Zumdahl Chemistry: Ch. 2 "Atoms, molecules, and ions"
Topics
Lab
"Elements, Compounds, Mixtures" lab using iron and sulfur.
Virtual labs:
BJU Chemistry: Ch. 2 "Matter"
AP Chem: Zumdahl Chemistry: Ch. 2 "Atoms, molecules, and ions"
Topics
- Elements, compounds, mixtures
- Physical and chemical properties
- States of matter
- Energy
- Temperature
Lab
"Elements, Compounds, Mixtures" lab using iron and sulfur.
Virtual labs:
- PhET Energy Forms and Changes weblab
- PhET States of Matter weblab
| 2._matter_handout__with_4_illustrations |
Below: The famous "Elephant Toothpaste" demonstration. It uses hydrogen peroxide (H2O2), liquid soap, and a catalyst such as manganese dioxide (MnO2) or potassium iodide (KI). The catalyst causes the H2O2 to rapidly break down, producing copious amounts of foaming oxygen gas.
Introduction
Chemistry is known as the 'Science of Matter' or 'The Central Science'. Everything we see in the Universe - all the matter - is made up of the elements listed on the Periodic Table. This is pretty amazing when you think about it.
People have had lots of ideas about matter. In the earliest historical records we have, the ancient peoples of the Near East refined and used copper, bronze, iron, and other metals which were very important to their military defense and their survival! In the Judeo-Christian and Muslim worldview, God creates matter, and then all life is fashioned from the matter. In contrast, in the Greek-Roman worldview, matter makes the gods, and the gods are like unruly kids in a big disfunctional family. In the modern 'materialist' worldview, matter makes man in an undirected process, and then man worships himself. The ancient Greeks spent quite a bit of time arguing about the existence of atoms and of the four elements - earth, water, air, and fire. The pre-Socratics (those before Socrates) argued that matter was comprised of atoms, and had a definite beginning, while Aristotle (after Socrates) argued that matter had no atoms (it was continuous, in other words) and didn't have a beginning (it had always existed).
Anyway, starting in the 1700's, when people started challenging Aristotle's ideas and actually setting up experiments and measuring things, very talented people like Priestly (England) and Lavoisier (France) were able to identify and do experiments with the gases of the atmosphere for the first time, and an exceptional experimenter named Dalton (England) was able to put together all their information and develop the Atomic Theory of Matter (1803). This was a big leap forward in our understanding of atoms and molecules! We are going to spend several lab sessions making and testing the gases of the atmosphere, using old-school glassware and chemicals.
Below: Dalton's "Elements" from around 1800.
Chemistry is known as the 'Science of Matter' or 'The Central Science'. Everything we see in the Universe - all the matter - is made up of the elements listed on the Periodic Table. This is pretty amazing when you think about it.
People have had lots of ideas about matter. In the earliest historical records we have, the ancient peoples of the Near East refined and used copper, bronze, iron, and other metals which were very important to their military defense and their survival! In the Judeo-Christian and Muslim worldview, God creates matter, and then all life is fashioned from the matter. In contrast, in the Greek-Roman worldview, matter makes the gods, and the gods are like unruly kids in a big disfunctional family. In the modern 'materialist' worldview, matter makes man in an undirected process, and then man worships himself. The ancient Greeks spent quite a bit of time arguing about the existence of atoms and of the four elements - earth, water, air, and fire. The pre-Socratics (those before Socrates) argued that matter was comprised of atoms, and had a definite beginning, while Aristotle (after Socrates) argued that matter had no atoms (it was continuous, in other words) and didn't have a beginning (it had always existed).
Anyway, starting in the 1700's, when people started challenging Aristotle's ideas and actually setting up experiments and measuring things, very talented people like Priestly (England) and Lavoisier (France) were able to identify and do experiments with the gases of the atmosphere for the first time, and an exceptional experimenter named Dalton (England) was able to put together all their information and develop the Atomic Theory of Matter (1803). This was a big leap forward in our understanding of atoms and molecules! We are going to spend several lab sessions making and testing the gases of the atmosphere, using old-school glassware and chemicals.
Below: Dalton's "Elements" from around 1800.
Lecture video: A simple video explaining the concepts in this chapter.
Lecture outline
Matter is anything that occupies space and has mass.
Atoms and molecules
Matter is anything that occupies space and has mass.
- Space is just another way of saying volume, which is measured in liters (L) or cubic meters (m3)
- Mass is measured in grams (g) or kilograms (kg)
Atoms and molecules
- All matter in the universe - including you! - is made up of one or more of the 'elements' on the Periodic Table - shown below.
- Any element by itself - Oxygen (O), Carbon (C), or Nitrogen (N) - is called an atom. The atom is the smallest unit of an element.
- When atoms combine, they form molecules. Examples are water (H2O), oxygen gas (O2), and carbon dioxide gas (CO2).
- Atoms and molecules are very small! Even the simplest living cell is made from trillions and trillions of atoms and molecules.
- Always bring your Sergeant-Welch Periodic Table to class! We will use it at practically every class session.
States of Matter, and the Kinetic-Molecular Theory
- Matter can exist as a solid, liquid, gas, or plasma
- All matter is comprised of particles which are in constant motion.
- Atoms and molecules are continually bouncing off each other, vibrating, and rotating - and even the bonds between atoms are vibrating as if connected by a spring. The molecules which make up the air in the classroom (principally nitrogen and oxygen) are moving at hundreds of miles per hour, colliding with nearby molecules, changing direction and moving again at hundreds of mph
Physical properties vs. Chemical properties
- Physical properties are things like size, weight, density, hardness, malleability, and physical state (solid, liquid, gas). Physical properties can easily be changed without a chemical reaction taking place.
- Chemical properties actually define what the compound *is*. Chemical properties must be changed through chemical reactions.
- When iron combines with sulfur (we will do this lab next time) it changes into an entirely new and different compound
- When cellulose cotton combines with nitric acid (we may do this later in the year, depending on time) it changes into something called 'nitrocellulose' which was discovered by accident and started the whole field of "polymers"
Elements, compounds, and mixtures
- An element is a pure substance that cannot be broken down into a simpler substance by chemical means. Elements are listed on the Periodic Table.
- A compound is a generic term referring to substances where at least 2 different elements are chemically combined. Examples: water, salt, iron sulfide
- A mixture can be separated into two or more pure substances using ordinary physical means (a filter, a magnet, a centrifuge, etc). Examples: gravel, dirt, air, blood, paint
Energy is defined as "the ability to do work"
- Kinetic Energy has to do with the motion of things. A moving car or bullet has 'kinetic energy'.
- Potential Energy has to do with position. The water behind a hydroelectric dam has 'potential energy'.
- 1st Law of Thermodynamics: "Matter and energy can't be created or destroyed, only converted from one form into another". This is known as the "Law of conservation of mass-energy".
- 2nd Law of Thermodynamics: "All spontaneous chemical reactions result in energy becoming spread-out, or dispersed."
- The 1st Law says, "You can never win", and the 2nd Law says, "You can't even break even". And that is true for all chemical reactions!
Temperature
- Temperature is a measure of the kinetic energy of the substance you're measuring
- In chemistry, we use Celsius and Kelvin to report temperature.
Advanced: Entropy
- Entropy is a quantitative measure of the amount of energy which is NOT available to do work. Example: The oceans contain lots of heat energy represented by the motion of water molecules; however, it is difficult to do "work" with this heat energy because it is relatively cool ~ 60-70 degrees F. It is interesting that people have tried this, by taking advantage of warm water on top and cooler water near the bottom; but it's not practical to do so.
- This energy is too spread out or 'disordered' to utilize. In this sense, Entropy can be thought of as "disorder"; but probably a more helpful term would be "dispersed".
- The basic idea is that all natural processes increase the entropy of a system. Energy is always trying to 'disperse' and spread out, in other words.
- The concept becomes useful when we're trying to predict whether a reaction will occur or not. This will come later in the course.
Auto Crash Bag research assignment
A car air bag explodes in just 1/100th of a second when you collide.
Research and submit a 1-1/2 to 2 page report. Your report will be graded on the following:
Reminder: Make sure your report includes:
A car air bag explodes in just 1/100th of a second when you collide.
Research and submit a 1-1/2 to 2 page report. Your report will be graded on the following:
- How does this happen, and what is going on chemically?
- Include sketches/diagrams of the mechanical parts,
- the chemical reactions taking place,
- sketches or models of the key molecules involved,
- and any relevant pictures.
Reminder: Make sure your report includes:
- Sketches/diagrams!
- Chemical reactions!
| auto_crash_bag_student_exemplar_papers.pdf |
Elements, compounds, and mixtures lab
- We will start off by observing and testing the properties of two common elements, iron (Fe) and sulfur (S). This includes dissolving the iron in acid and trying to dissolve (unsuccessfully) the pure sulfur in various things.
- Then we will carry out a reaction which combines the Fe and S to form FeS, a completely new compound with a different appearance and properties.
- After that, we will react a small amount of the FeS with hydrochloric acid (HCl) to form hydrogen sulfide gas (H2S) which has quite different (and noticeable!) properties.
- Finally, we will bubble some of the H2S into a water sample, to demonstrate one way you could remove heavy metals from wastewater.
- All of this serves as an excellent introduction to elements and compounds, and setting up chemical reactions.
| _elements_compounds_mixtures_lab_handout_.pdf |
Matter homework questions
| matter_homework_questions.docx |