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Presentation on theme: "Matter."— Presentation transcript:

1 Matter

2 Origins of the Idea Democritus (~400 BCE)
Matter is composed of atoms Atoms are eternal, invisible, indivisible, and incompressible Greeks believed in 3 phases or states of matter Solid, liquid, gas We now add plasma as the fourth phase

3 Matter in the Universe 99% of the known matter in the universe is Hydrogen and Helium The majority of the known matter is in the form of a plasma in stellar interiors The average density of the known matter in the universe is such that 1 gram would occupy a volume 30 x that of Earth The location and characteristics of most of the matter in the universe is unknown – dark matter

4 Antimatter A matter particle and an antimatter particle are the same with the exception of charge and magnetic properties (which are opposite). Naturally formed and man-made. When matter and antimatter particles collide, they annihilate each other.

5 Elements Fundamental forms of matter
Can’t be broken apart by normal means 92 occur naturally on Earth They are the same everywhere


7 What Are Atoms? Smallest particles that retain the distinguishing physical and chemical properties of an element Made up of subatomic particles: Protons (+) Electrons (-) Neutrons (no charge)

8 Examples of Atoms electron proton neutron Hydrogen Helium

9 Chemical Bonds, Molecules, & Compounds
Bond is union between electron structures of atoms Atoms bond to form molecules Molecules may contain atoms of only one element - O2 Molecules of compounds contain more than one element - H2O

10 Atomic Number 6C12 6C13 6C14 Number of protons
All atoms of an element have the same atomic number Atomic number of hydrogen = 1 Atomic number of carbon = 6

11 Isotopes vary in mass number
6C12 6C13 6C14 Number of protons + Number of neutrons Isotopes vary in mass number

12 Isotopes Atoms of an element with different numbers of neutrons (different mass numbers) Carbon 12 has 6 protons, 6 neutrons Carbon 14 has 6 protons, 8 neutrons 6C12 6C13 6C14

13 Chemical Origins Most chemical elements were created after the Big Bang in subsequent generations of stars. Nucleosynthesis: primordial (H, He, Li) stellar (He -> Fe) explosive (Co -> …)

14 Radioisotopes - Radioactivity
Have an unstable nucleus that emits energy and particles a particles – 2 protons and 2 neutrons b particles – an electron g rays – a high energy photon Radioactive decay transforms radioisotope into a different element Decay occurs at a fixed rate Because decay happens at a fixed rate, you can use it for age dating! (C14 has a half-life of 5,700 years.)

15 The Age of the Solar System
Ages of rocks can be measured through radioactive dating: Measure abundance of a radioactively decaying element to find the time since formation of the rock Dating of rocks on Earth, on the Moon, and meteorites all give ages of ~ 4.6 billion years.

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