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1

"Standard Model"

What our current understanding of subatomic particles is known as

2

Atom

building block of matter

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Element

Material composed of only one kind of atom

4

How many elements are known?

115. 90 occur naturally.

5

Every simple, complexing, living, or nonliving substance in the known universe is put together...

from a pantry containing less than 100 elements.

6

Atoms are so small that there are about...

10^23 atoms in a gram of water.

7

Atoms in body have been around since...

more than 4.6 billion years ago.

8

Brownian motion

perpetual jiggling of particles that are just large enough to be seen.

9

Brownian motion is evidence...

that atoms exist, as it results from the motion of neighboring atoms and molecules. They bump into the larger particles that we can see.

10

Molecule

Smallest particle of a substance consisting of two or more atoms that bond together by sharing electrons.

11

Molecules can be made up of...

atoms of the same element or of different elements.

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Compound

Substance that is made of atoms of different elements combined in a fixed proportion.

13

Chemical formula

Tells the proportions of each kind of atom for a compound.

14

Compounds have properties different from those of...

the elements of which they are made.

15

Nucleus

Where almost all of an atom's mass is packed into a dense central region.

16

Nucleons

Principal building blocks of the nucleus.

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Neutrons

Nucleons in an electrically neutral state

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Protons

Nucleons in an electrically charged state

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Isotope

Atoms of the same element having different numbers of neutrons.

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Deuterium

When proton is accompanied by a neutron

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Tritium

When two neutrons are in a hydrogen nucleus.

22

Atomic number

The number of protons in the nucleus.

23

Ion

Atom with a net charge.

24

Shell model of atom

-electrons are pictured as orbiting in spherical shells around the nucleus.
-there are seven different shells, each has its own capacity for electrons

25

The arrangement of electrons in the shells around the atomic nucleus dictates...

the atom's chemical properties.

26

Four phases of matter

Solid, liquid, gaseous, and plasma

27

Plasma

Consists of positive ions and free electrons. Phase exists only at high temperatures.

28

Crystals

Regular geometric shapes whose component particles are arranged in an orderly, repeating pattern.

29

The shape of a crystal mirrors the...

geometric arrangement of atoms within the crystal.

30

Density

Measure of how much matter occupies a given space.
density = mass/volume