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Flashcards in Chapter 2 Deck (61):
1

Scanning tunneling microscopy (STM)

a technique that can image, and even move, individual atoms and molecules

2

tunneling current

the electrical current that flows between the tip of the electrode and the surface even though the two are not in physical contact

3

The smalles identifiable unit of an element

atom

4

the law of conservation of mass

In a chemical reaction, matter is neither created nor destroyed

5

Antoine Lavoisier formulated this law

the law of conservation of mass

6

Joseph Proust observed this law

The law of definite proportions

7

the law of definite proportions

All samples of a given compound, regardless of their source or how they are prepared, have the same proportions of their constituent elements

8

John Dalton stated this law

the law of multiple proportions

9

the law of multiple proportions

When two elements (A and B) form two different compounds, the masses of element B that combine with 1g of element A can be expressed as a ratio of small whole numbers.

10

John Dalton stated this theory

atomic theory

11

Atomic theory

1. each element is composed of tine, indestructible particles called atoms
2. all atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements
3. atoms combine in simple, whole-numbered ratios to form compounds
4. atoms of one element cannot change into atoms of another element.

12

J.J. Thompson used this to discover electrons

cathode rays in a cathode ray tube

13

electron

negatively charged, low mass partical present within all atoms

14

electrostatic forces

electrical charge is a fundamental property of some of the particles that compose atoms and results in attractive and repulsive forces

15

electric field

An area around a charged particle where electrostatic forces exist

16

J.J. Thompson discovered this

Electrons

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Robert Millikan

discovered the charge of a single electron with his oil drop experiment

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Electron charge

-1.60 x 10^-19 C

19

Electron mass

.00091 x 10^-27 kg

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Radioactivity

the emission of small energetic particles from the core of certain unstable atoms

21

Henri Becquerel and Marie Curie discovered this

radioactivity

22

Rutherford proposed this

nuclear theory, after completing his gold foil experiment

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nuclear theory states

1. Most of the atom's mass and all of its positive charge are contained in a small core called the nucleus
2. most of the volume of the atom is empty space, throught which tine, negatively charged electrons are dispersed
3. there are as many negatively charged electrons outside of the nucleus as there are positively charged particals withing the nucleus, so the atom is electrically neutral

24

neutrons

neutral particles withing the nucleus, with mass similar to a proton

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James chadwick found these

neutrons

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Atomic Mass Unit (AMU)

defined as 1/12 the mass of a carbon atom containing six protons and six neutrons

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proton mass

1.672 x 10^-27 kg

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proton charge

+1.602 x 10^-19 C

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neutron mass

1.674 x 10^-27 kg

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neutron charge

0

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Defines an element

the number of protons

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atomic number

the number of protons in an element

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chemical symbol

one or two letter abbreviation listed directly below its atomic number

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Elements chemical symbols and names come from

English names, latin names, names to reflect properties, and astronomical bodies, and scientist who discovered it

35

Isotope

Atoms with the same number of protons but different numbers of neutrons

36

Natural abundance

the percentage of the individual isotopes found in nature

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mass number

the sum of the number of neurons and protons in an atom

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Ions

When an atoms loses or gains and electron

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Cation

positively charged ion

40

anion

negatively charged ion

41

Dmitri Mendeleev

created the periodic table, and stated the periodic law

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periodic law

When elements are arranged in order of increasing mass, certain sets of properties recur periodically

43

Classifications of elements in the periodic table

metals, nonmetals, metalloids

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metals

lie on the lower left side and middle of the periodic table and share some common properties. good conductors, malleability, ductility, often shiny, and tend to lose electrons when they undergo chemical changes

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nonmetals

lie on the upper right side of the periodic table. varied properties(solid, liquid, gas), tend to be poor conductors, and they tend to gain electrons when they undergo chemical changes.

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metalloids

lie alone the zigzag diagonal line that divides metals and nonmetals. exhibit mixed properties. some are classified as semiconductors

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semiconductors

The classification for several metalloids, because of their intermediat and highly temperature dependent electrical conductivity. the ability to change and control conductivity makes them useful in making electronic chips and circuits.

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main group elements

properties tend to be largely predictable based on their position in the periodic table. 1a-2a, 3a-8a

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transition elements or transition metals

properties tend to be less predictable based on their position in the periodic table. 3b-8b, 1b-2b

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family or group

each column within the main-group regions of the periodic table

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Noble gasses

mostly unreactive, 8a

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alkali metals

reactive metals, 1a

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alkaline earth metals

fairly reactive, although not as reactive as alkali metals, 2a

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halogens

very reactive nonmetals, 7a

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Predicting ions (2 ways)

1. main group metal tends to lose electrons, forming a cation with the same number of electrons as the nearest noble gas
2. main group nonmetals tend to gain electrons, forming an anion with the same number of elctrons at the nearest noble gas

56

Atomic mass

calculation of the average mass of an element found by taking the percent natural abundance found of each isotope.

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Mole

the amount of a material containing 6.022 x 10^23 particles

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avogadros number

6.022 x10^23 particles,

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How does the mole get its specific value

the value of the mole is equal to the number of atoms in exactly 12 grams of pure carbon-12

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1 mole = (particles, grams)

6.022 x 10^23 particles, atomic mass # of grams

61

molar mass

an element's molar mass in grams per mole is numerically equal to the element's atomic mass in atomic mass units