Unit 2: Environmental Systems Mr. Ross Brown Brooklyn School for Law and Technology

How is matter conserved in all chemical and biological systems? 13 Oct 2017 Do now: Kindly take a copy of the Mono Lake reading from my low desk. Begin reading and annotating right away. In your notebook, please use a few minutes and write freely about the subject of the article and what you think about this story. Work on this until 11:30

How is matter conserved in all chemical and biological systems?

How is matter conserved in all chemical and biological systems? What do hot dogs, Ferraris, your shirt, the ocean, the Sun, and your lips have in common? Matter: anything that occupies space and has mass. Mass: the amount of matter something contains Not weight!

How is matter conserved in all chemical and biological systems? All matter can be broken down into smaller pieces Atom: smallest particle that contains the chemical properties of an element Element: substance composed of atoms that cannot be broken into simpler parts 94 on Earth, 24 more in the lab; Periodic table Molecules contain more than one atom Compounds contain more than one element

How does matter behave at the elemental level? Sub-atomic level Number of protons is constant All Carbon has 6 protons Sometimes, number of neutrons changes Isotopes: same element, different number of neutrons, thus different mass number

How does matter behave at the elemental level? Some isotopes are radioactive, or unstable. They spontaneously release material from the nucleus, or go through radioactive decay Uranium-235 (235U) decays to form thorium-231 (231Th). The lost mass becomes energy. 235U is parent, 231Th is daughter or child.

How does matter behave at the elemental level? We measure the rate of decay as half-life, the time it takes for ½ of the radioactive parent to decay. Many half-lives are very loooooooooong. 14C has a half-life of 5,730 years, useful for dating fossils

How does matter behave at the elemental level? How are atoms held together as molecules or compounds? Covalent bonds: electrons are shared. Strongest!

How does matter behave at the elemental level? Ionic bonds: electrons get transferred, so one atom becomes positive and one negative. NaCl: salt Weaker

How does matter behave at the elemental level? Hydrogen bonds: hydrogen atoms that are covalently bonded to one atom are attracted to an another on another molecule Water (H2O or HOH) is a polar molecule, unequally distributed electrons.

How does energy flow within and among systems? Energy: the ability to do work joule: basic unit of energy. Powers a 1-watt bulb for 1 second. There are other units. Power: the rate at which work is done energy=power*time power=energy/time

How does energy flow within and among systems?

How does energy flow within and among systems? Forms of energy Electromagnetic radiation: energy from the Sun Visible light, ultraviolet, infrared Carried by photons, massless packets of energy traveling at the speed of light

How does energy flow within and among systems? Potential energy: energy that is stored but not yet released. Chemical energy: stored in bonds, like your food!

How does energy flow within and among systems? Kinetic energy: the energy of motion! Energy moves matter, even on the atomic level. The average kinetic energy of a substance is its temperature.

How does energy flow within and among systems? Energy converts from potential to kinetic and back again 1st Law of Thermodynamics: energy is neither created or destroyed but can change form

How does energy flow within and among systems? 2nd Law of Thermodynamics: when energy is transformed, the quantity remains the same, but its ability to do work diminishes

How does energy flow within and among systems? Energy flow within a system Open systems: exchanges of matter and energy occur across boundaries Closed: exchanges do not occur A lake? new water and animals and things enter, things exit Earth? open regarding energy, but gravity makes it closed regarding matter. There are inputs and outputs  Systems Analysis

How does energy flow within and among systems? If inputs equal outputs  Steady State Feedbacks: adjustments to inputs or outputs. Can be positive or negative

How does energy flow within and among systems?

How does energy flow within and among systems? I am super-sorry I will be away tomorrow. It is unavoidable. While I am away, please work together to write up a summary of your notes so far. Please share notes. Remember, this assessment later this week is not from me. I am approaching it with a positive attitude, and I need you to, too.

How does energy flow within and among systems?