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Chapter 4.1 Introduction to Atoms

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David Thaggard

on 14 October 2015

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Transcript of Chapter 4.1 Introduction to Atoms

Grade 8 Physical Science

Chapter 4.1
Intro to Atoms

Scientists hypothesized about atoms, the smallest and most basic unit of matter, more than 2000 years ago, but it was only about 400 years ago that they actually began testing that hypothesis
So, there was this guy Dalton (boo). Building on the work of previous scientists, his theory combined their work into one "unifying" theory that describes how matter and atoms are related. It goes something like this:
#1--All matter is made of atoms
#2--The atoms of any element are identical, or exactly the same, as each other. So, gold atoms are always going to be the same, no matter where they are AND they'll always be different from other atoms, like, say, that sissy element silver.
#3--Atoms can't be changed into other atoms (later, this idea would be called the Law of Conservation of Matter). In fact, the only thing you can do is rearrange the combinations of atoms.
#4--Speaking of combinations, Dalton said that compounds (different from elements, but they're both substances) are made up of different types of atoms chemically bound into molecules in specific ratios (like water-->H2o).
Now, this may not seem like a big deal but for a very long time people weren't sure about matter and how changes in it occurred, so Dalton's theory did a nice job of answering several basic questions about matter, and laying the groundwork for proper Scientific Inquiry.
Dalton's Theory of Atomic Structure
heh heh heh. this is funny.
So, atoms have to be made of stuff, too, right? Here's how that works. Every atom is made of three particles
Protons, which have Positive charges and are very dense (or heavy, if that helps)
Neutrons, which have Neutral charges and are also very dense (still heavy)
Electrons, which have Negative (or Evil--get it? "E" for "electron," and "e" for "evil" and negative can be bad like evil) charges and are not at all dense (very light, if that still helps)
Atomic Structure and Particles
The Nucleus is where you find the Protons and Neutrons. Electrons circle around the Nucleus. You need all three parts, arranged in this pattern, to have an atom.

In any atom, the number of Protons and Electrons is the same (mostly, but that's for chemistry) and, usually, so too is the number of Neutrons.
Now, it's not enough just to know what's in an atom. Knowing where each particle can be found is critical to understanding how atoms and molecules and matter work.
Isotopes are where atoms (and elements) can get a little weird. You see, an isotope is an atom that has a different number of neutrons than it normally does.
Isotopes: Atomic Cousins
The history of all that testing is interesting to some people, but isn't terribly exciting to most. So, let's just say that an English (boo!) chemist by the name Dalton came up with a theory that describes how atoms work.
sorry, this is a lousy picture. i tried getting something to do with Dalton from the internet, and there was a ton of stuff, but you might be surprised because all of it was crap. i wasn't surprised, because i know Dalton was English, and i already knew that about the English.
The cool thing is, as weird as isotopes are, chemically they behave just like a normal atom of the same element (we're packed full of carbon isotopes, and you don't hear your bodies complain). The only time you really have to worry about them is when you hear about radiation.
maybe this helps?
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