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Basic Chemistry > Unit 2: Atoms > Flashcards

Unit 2: Atoms Flashcards

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1
Q

nucleus

A

Contains all of the positive charge and most of the mass of a atom

Central core of an atom which contains the protons (1 or more) and neutrons

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2
Q

atomic number

A

The number of protons in the nucleus of an atom of a given element

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3
Q

orbital (Schrödinger Model)

A

3-dimensional region of space with a good chance of containing an electron

Schrödinger’s model is very mathematical; electrons are described in terms of wavefunctions and probabilities rather than absolute positions

Electrons do not live in orbits, they live in orbitals

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4
Q

abbreviated electron configuration

A

AKA core notation

Core electrons are substituted by the symol of the noble gas in square brackets

EX: Mg = [Ne] 3s2

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5
Q

What is a group in the periodic table?

A

A column in the periodic table

AKA family

Elements in the same column of the periodic table have similar chemistry

Many families have special names; elements in a family often have similar names due to their similar reactivity

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6
Q

What is a period in the periodic table?

A

A row in the periodic table

Elements in the same row of the periodic table have different chemistry

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7
Q

core electrons

A

All of the electrons that are not in the highest energy level, these electrons are very stable and will rarely get involved in reactions

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8
Q

photon

A

A “unit” or “packet” of radient energy

A particle representing a quantum of light or other electromagnetic radiation

A photon carries energy proportional to the radiation frequency but has zero rest mass

Have wavelength properties, they travel through space as oscillating electric and magnetic fields

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9
Q

Planck’s constant

A

Special value in quantum mechanics

Symbol: h

Value: 6.626 x 10-34 Js

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10
Q

orbital energy diagram

A

A conventient tool for understanding the energy of orbitals

The boxes are arranged from bottom to top in order of increasing energy

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11
Q

chemical reaction

A

Chemical change

A process in which 1 or more substances are converted into new substances that have compositions and properties different from those of the original substance

Cannot change the number of protons or neutrons in any atoms but easily changes the number of electrons

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12
Q

classical mechanics

A

Developed by Isaac Newton

A mathematical model for the rules governing the motion of bodies

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13
Q

continuous spectrum

A

A spectrum in which all the visible wavelengths are present

Violet: 400nm

Red: 750nm

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14
Q

eletromagnetic radiation

A

AKA radiant energy, light

Form of energy carried by photons, a “unit” or “packet” of radiant energy

A form of energy that can be described in terms of oscillating waves that move through space at the speed of light

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15
Q

electron

A

A negatively charged particle “inside” of the atom

All electrons are identical and all atoms “contain” electrons

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16
Q

electronic transitions

A

Occurs when an electron “moves” from one orbit to another (Bohr model)

When an electron absorbs energy it moves to a higher orbit (n increases)

When an electron emits energy it moves to a lower orbit (n decreases)

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17
Q

proton

A

Has a positive charge

Number of protons is identity of an element

Charge: +1.6022 x 10-19C

Relative charge: +1

Mass: 1.6726219 x 10-24g (1,836 times more than an electron)

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18
Q

quantized

A

Can have only certain values

Bohr suggested that the energies of electrons in an atom are quantized.

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19
Q

quantum mechanics

A

Highly mathematical topic that describes the behavior of electrons in an atom (we’ll ignore the math and work with descriptive terms and memorization)

Quantum numbers = address of electrons

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20
Q

speed of light

A

All photons travel at the same velocity - the speed of light

Symbol: c

Value: 3.0 x 108 m/s

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21
Q

white light

A

A source that contains all wavelengths of light

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22
Q

nuclear reaction

A

Can alter the total amount of mass but this is only important in very high energy environments like a star

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23
Q

ion

A

Charged atom

Contains a different number of protons and electrons

The charge of an ion is equal to the difference

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24
Q

isotope

A

Atoms that share the same number of protons but a different number of neutrons are known as isotopes of the same element

Isotopes disprove one of Dalton’s postulates - that all atoms of an element have the same mass

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25
Q

isotope symbol

A

Communicates the full subatomic structure of an isotope by listing the mass number, atomic number and element symbol

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26
Q

line spectra of the elements

A

Bohr model of the atom

The line spectra of the elements were collected by placing a small sample of an element in an evacuated glass tube, passing an electric current through the tube to produce excited atoms, collecting the light emitted from the tubes as the atoms relax to the ground state, and passing that light through a prism.

The data collected shows that excited atoms produces a line specrum rather than a continuous spectrum

Atoms cannot emit any arbitrary amount of energy, only certain special amounts of energy can be involved.

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27
Q

mass number

A

Total number off protons and neutrons in the nucleus

28
Q

neutral atom

A

Contais the same number of protons and electrons

29
Q

neutron

A

Similar to proton but carries no charge

Found in 1932 by James Chadwick

Number of neutrons is not specific to an element; determines the isotope

Charge: 0C

Relative charge: 0

Mass: 1.6749 x 10-24g (tiny bit more than proton)

30
Q

atomic mass

A

Mass (in grams) of 1 mole of that element

Population weighted average of the isotopic masses for that element

31
Q

Dalton’s Atomic Theory

A

4 postulates:

  1. All matter is composed of exceedingly small, indivisible particles called atoms
  2. All atoms of a given element are identical both in mass and in chemical properties
  3. Atoms are not created or destroyed in chemical reactions
  4. Atoms combine in simple, fixed, whole-number ratios to form compounds

* underlined items were proven wrong *

32
Q

valence electrons

A

Electrons that are not core electrons

Reside in the highest energy level and are the least stable electrons in the atom

All of the chemistry that an element does depends on the number of valence electrons it contains

The number of valence electrons equals the roman numeral in the column name. EX: P is in VA(15) so it has 5 valence electrons

33
Q

energy of light

A

The energy carried y a photon is directly proportional to its frequency

Symbol: E

Units: J (joules)

34
Q

angular momentum quantum number

A

Second quantum number, Schrödinger Model

Determines the shape and energy sublevel of an orbital

Symbol: l (lower case l)

Values: 0, 1, 2, … n-1

For values of n, there are 1 or more values of l

35
Q

metallic character

A

Periodic trend - metallic character increases:

  • from right to left
  • from top to bottom
36
Q

Hund’s rule

A

States that electrons are distributed into orbitals of equal energy in a way that maximizes unpaired electrons

EX: p orbital for Nitrogen

37
Q

Oil Drop Experiment

A

Conducted by Robert Millikan in 1909 to measure the mass and charge of the electron

Charge of electron: -1.6022 x 10-19 C

Relative charge: -1

Mass: 9.1094 x 10-28 g

38
Q

aufbau principle

A

From the German ‘auf bauen’, ‘to build up’

Electrons fill orbitals starting with the lowest-energy orbitals

39
Q

electron configuration

A

Notation used to list all the filled orbitals

  • orbitals are listed from left to right in order of increasing energy
  • given a superscript to the right to indicate how many electrons they contain
  • unfilled orbitals are not listed
40
Q

ionization energy

A

Measures how hard it is to lose an electron for the different elements (energy needed to make an ion) - valence electrons are much easier to remove than core electrons

Atoms can lose multiple electrons and have multiple ionization energies

Periodic trend - first ionization energy of the elements tend to increase:

  • from left to right
  • from bottom to top
41
Q

Plum Pudding Model

A

Proposed by J.J. Thomson in 1904 to address the negative and positive charge

The model proposed atoms contained electrons embedded in a uniform sphere of positive charge

* Further experiments verified that the atom does contain positive charge BUT it is not a uniform distribution *

42
Q

Pauli exclusion principle

A

States that no 2 electrons in an atom can share quantum numbers (address)

A maximum of 2 electrons can occupy each orbital and they must have opposit spins

43
Q

Bohr Model

A

Niels Bohr suggested the planetary model of the atom in 1913 to explain the line spectra of the elements; focused on Hydrogen - 1 proton and 1 electron; didn’t work for atoms with >1 electron

Proposed electrons orbit the nucleus of the atom much like planets in the solar system orbit the sun

These orbits were fixed at certain distances and an electron in an orbit was stable

Each orbit was given a value n, a positive integer with 1 being the one closest to the nucleus

The lines in the spectra were the result of electronic transitions

44
Q

Cathode Ray Experiment

A

Conducted in 1897 by JJ Thomson

Demonstrated that the atom was not indestructible

Credited with the discovery of the electron

45
Q

periodic table and electron configurations

A

Each row of the periodic table represents a value of n - d orbital is off by 1 and f by 2

Each block of the periodic table represens a value of l

The number of columns in each block is determined by the values of m and ms

46
Q

spin magnetic quantum number

A

Fourth quantum number

Determines the spin of the electron

Symbol: ms

Values: +/- 1/2 (has only 2 values

Each orbital can contain 2 electrons of opposite spin, this is usually drawn as arrows pointing up and down within a box on an orbital diagram

47
Q

diatomic elements

A

Found in nature as 2 atoms bound together, rather than as single atoms

Have H2 Hydrogen

No N2 Nitrogen

Fear F2 Flourine

Of O2 Oxygen

Ice I2 Iodine

Cold Cl2 Chlorine

Beer Br2 Bromine

48
Q

electromagnetic spectrum

A

All the different forms of electromagnetic radiation

49
Q

principal quantum number

A

First quantum number, Schrödinger Model

Determines the size and energy level of an orbital

Symbol: n

Value: any positive integer (1, 2, 3, …)

50
Q

Gold Foil Experiment

A

Demonstrated that the atom is not uniformly positive

Conducted in 1908 by Ernest Rutherford

The positive charge of the atom is contained in a very small region at the center of the atom

51
Q

law of conservation of mass

A

Matter cannot be created or destroyed during a chemical reaction (except in nuclear reactions)

It can change forms during a reaction but there will always be the same total amount

1787 - experimental work by Antoine Lavoisier led to the law

52
Q

law of conservation of energy

A

During a chemical or physical change, energy can be transferred or it can change forms but the total amount of energy remains constant, it cannot be created or destroyed

53
Q

law of definite proportions

A

All samples of a given compound contain the same proportion, by mass, of the elements they contain

EX: Water (H2O) contains the same proportion of hydrogen and oxygen no matter where the sample comes from

Mass Ratio: 8:1

Volume Ratio: 1:2

1804 - experiemental work of Joseph Proust led to the law

54
Q

law of multiple proportions

A

In circumstances where 2 or more elements make a series of compounds together, the relative mass proportions of the elements follows a pattern

EX: water (H2O) and hydrogen peroxide (H2O2) both contain H & O

If a water sample has 2 g of H, it has 16g of O

If a hydrogen peroxide sample has 2 g of H, it has 32g of O

The ratio of masses of O between the two is 1:2 which is a small-whole number ratio

1808 - experimental work of John Dalton led to the law

55
Q

magnetic quantum number

A

Third quantum number, Schrödinger Model

Determines the orientation of an orbital and the total nuber of orbitals in an energy sublevel

Symbol: m

Values: -l, -l+1, … , 0, …, l-1, l

For each value of l, there are 1 or more values of m

56
Q

frequency

A

Number of wave cycles that pass a point per second

Symbol: v (Greek letter nu)

Units: Hz (hertz) or s-1 or 1/s (inverse seconds)

The frequency of electromagnetic radiation is inversely proportional to its wavelength

57
Q

wavelength

A

Distance between repeating parts of the wave

Symbol: (Greek letter lambda)

Units: m (meters)

The wavelength of electromagnetic radiation is inversely proportional to its frequency

58
Q

Shrödinger Model

A

nlm

n = principal quantum number: 1, 2, 3, …

l = angular momentum quantum number: s, p, d, f

m = magnetic quantum number: x, y, z

59
Q

What are the family names in the periodic table?

A
60
Q

prefix units

A

Prefix__Symbol__Factor giga G 109 mega M 106 kilo k 103 deci d 10-1 centi c 10-2 milli m 10-3 micro µ 10-6 nano n 10-9 pico p 10-12

61
Q

closed-shell or noble gas electron configuration

A

The elements tend to gain or lose electrons to achieve a closed-shell or noble gas electron configuration

The charges on the most stable ions of the elements also follows a periodic trend

  • elements to the left of the periodic table tend to form stable cations by losing electrons
  • elements to the right of the periodic table tend to form stable anions by gaining electrons
62
Q

cation

A

An atom that loses an electron and becomes a positively charged ion

Atoms can gain or lose more than one electron but rarely more than 3

EX: Na+

Mg2+

Tend to be smaller than the neutral atoms they came from

63
Q

What is periodicity of the elements’ physical and chemical properties?

A

Periodicity was recognized by Dmitri Mendeleev and he used that to create periodic table btw 1869 & 1871

Recurring at intervals

64
Q

atomic size

A

The size of an atom is a bit difficult to define because the position of the electrons is not well defined

AKA atomic radius

Atoms get much larger at the beginning of each row and then shrink within the row

65
Q

anion

A

An atom that gains an electron and becomes a negatively charged ion

Atoms can gain or lose more than 1 electrons but rarely more than 3

Tends to be bigger than the neutral atoms they came from

66
Q

atomic mass unit (amu)

A

1 amu = 1.6606 x 10-24 g

measurement unit for atomic mass

basic unit of mass of atoms and molecules

exacltly 1/12 the mass of 12C atom

Basic Chemistry (7 decks)

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