CH2) Atoms, Molecules, and Ions

Question 1

Structure of Matter

Atoms

Answer 1

Composed of electrons, protons and neutrons

Question 2

The structure of matter

Molecules

Answer 2

Combination of atoms

Question 3

the structure of matter

Ions

Answer 3

charged particles

Question 4

Jhon Dalton and Atomic theory

Answer 4

• Different conbinations produce different compounds
• Atoms of difference elements have different masses
• no atom disapears or is changed in chemical reaction

Question 5

Fundamental laws of matter

3 fundamental laws of matter

Answer 5

• law of conservation of mass
• lasw of constant composition
• laws of multiple proportions

Question 6

Components of the Atom

what are atoms made of? and how do we know that?

Question 7

The elctron and the Atom

Answer 7

• every atom has at least one electron
• atoms are known that have one hundred or more electrons
• there is one elctron for each positive charge in an atom
• electrical neutrality us maintained

Question 8

The plum-pudding Model

Answer 8

• J.J thomson proposed the atom as a positively charged spehere
• whithin the spehere are eletrons
• Plum-pudding or raisin-bread model

Question 9

Protns and Neutrons- The nucleus

Answer 9

• 1911 Rutherford bombarded of gold foil with a particle (helium atom without electrons)
• Expected to see the particles pass through the foil
• Found that some of the aplha particles were deflected by the foil
• led to the discovery of a region of heavy mass at the center of the atom

Question 10

Rutherdord’s model

Answer 10

• rutherford’s exoeriment revealed a small, dense core with positive charge
• electrons are outside this core
• most of the atom is empty space

Question 11

Nuclear Particles

1) protons

Answer 11

• mass nearly eqaul to the H atom
• positive charge

Question 12

2) Neutrons- Discovered by Chadwick in 1934

Answer 12

• mass slightly greater than that of the proton
• no charge

Question 13

Mass and the atom

Answer 13

• more than 99% of the atomic mass is concentrated in the nucleus

Question 14

Termininology

Atomic number, z

Answer 14

• number of protons in the atom

Question 15

Mass number, A

Answer 15

• number of protons plus number of neutrons
• A is the mass number
• Z is the atomic number
• X is the chemical sysmbol

Question 16

Examples

1) An isotope of cobalt(z+27) is used in radiation cancer therapy, it has 33 neutrons, what is its nuclear symbol?

Question 17

Isotopes

Answer 17

• 2 atoms of the same element
• same atomic number
• different mass numbers
• number of neutrons is A minus Z
• number odf neutrons differs between isotopes

Question 18

Isotopes of hydrogen

Answer 18

• 1H, 2h, 3h
• hydrogen, deuterium, tritium
• different masses

Question 19

Atomic Masses: The carbon-12 scale

Answer 19

• Unit is the atomic mass unit (amu)
• Mass of one 12C atom= 12 amu (exactly)
• Note that 12C and C-12 mean the same thing

Question 20

Determine Atomic Masses

Answer 20

• can be determined to highly

Question 21

isotopic abundance

Answer 21

• determine hte mass of an element, we must know the mass

Question 22

Mass Spectrum of CI

Answer 22

• the mass spectrum is a plot of abundance vs. mass
• the area under the peak in the mass spectogram gives the isotopic abundance

Question 23

Carbon

Answer 23

• 12

Question 24

Isotopic Abudance

Answer 24

• determine the mass of an element, we must know the mass of each isotope and the atom perfent of the isitopes (isotopic abundance)

Question 25

Masses of individuals atoms

Answer 25

- many porpouses, relative masses- not sufficient - necessary to know the mass of an atom in grams- quatitiy of matter can be determine weighing - number that converts the mass of an atom in atomic mass units

Question 26

Examples: NB. 6.022x10^23=

Answer 26

atomic mass in grams

Question 27

# Periods and groups horixzontal rows are **periods**

Answer 27

- first period is H and He - Second period is Li-Ne -

Question 29

# Blocks in the periodidc table main groups elements

Answer 29

1,2,13-18

Question 30

transition metals

Answer 30

- 3-12

Question 31

post transition metals

Answer 31

- Elements in groups 13-15 to the right of the transition metals - Ga, In, Ti, Sn, PB, Bi, Po

Question 32

# Groups with common names group 1:

Answer 32

Alkali metals

Question 33

group 2

Answer 33

Alkali earths

Question 34

group 3

Answer 34

noble or inert gases

Question 35

group 4

Answer 35

helogens

Question 36

group 5

Answer 36

chalcogenes

Question 37

group 6

Answer 37

Pnictogens

Question 38

Importance of group

Answer 38

similar chemical properties

Question 39

Mendeleev

Answer 39

- Dmitri mendeleev, 1836-1907 - Arranged elements by chemical properties -

Question 40

Metals and nonmetals

Question 41

Some elements

Answer 41

- Sulfur (nonmetal), antimony(metalloid) and silver (metal)

Question 42

Molecules

Answer 42

2 or more atoms may combine to form a molecule - atoms involved are often nonmetals - covalent bonds are strong forces that hold the atoms together

Question 43

Molecular Formulas

Answer 43

- Number of each atom is indicated

Question 44

Structrurals formula

Answer 44

show bonding patterns within the molecule

Question 45

Condensed Structural formulas

Answer 45

suggest the bonding pattern and highlight specific parts of a molecule. Such as the reactive group of

Question 46

Molecular Elements

Answer 46

- some exist as molecules, including such common ones as oxygen, hydrogen and nitrogen

Question 47

Ions

Answer 47

- when atoms or molecules lose or gain electrons, they form changed particles called **ions** - Na->Na+ +e- - O+ 2e- ->O^2- - Cation (+) - Anions (-) - no change in number of protons in the nucleus when an ion forms

Question 48

Polyatomic ions

Answer 48

- groups of atoms may carry a charge; these are polyatomic ions - Oh-, hYDROGEN ION - NH4+, ammonium ion

Question 49

Ionic Compounds

Answer 49

- Compounds can form between anions and cations - Sodium cloride, Nacl

Question 50

forces between ions

Answer 50

- Ionic compounds are hekd together bby strong forces called ionic bonds - Electrostatic attraction of + and - for each other - compounds are usually solids at room temperature - high melting points - may be water- soluble

Question 51

Solutions pf inoic compounds

Answer 51

- when and ionic compound dissolves in water, the ions are relaae from each other - presence of ions in the solution leads to electrical conductivity - strong electrolytes - when molecular compounds dissolce in water, no ions are formed - without ions, solutions does not conduct

Question 52

Formulas of ionic compounds

Answer 52

- charge balance - each positive charge must have a negative charge to balance it - ccalsium chloride, CaCl 2 - Ca2+ - two Cl- ions are required for charge balance

Question 53

Noble gas connections

Answer 53

Atoms close to a noble gas (group18) form ions- conatin same number of electrons as the neighboring noble gas atom - Applies to Groups 1,2,16 and 17, plus AI (Ai3+) AND N(N3)

Question 54

Cations of transitions and Post-transition metals - Iron

Answer 54

Commonly forms Fe2+ and Fe3+

Question 55

Lead

Answer 55

- commonly forms Pb2+ and Pb4+

Question 56

Polyatomic ions

Answer 56

There are only 2 common polyatomic cations - NH4+ and Hg2^