Chapter 2 Flashcards
The ancien Greeks believed that there were __#__ elements. Give the number of element and state them.
4 earth fire water air
Who proposed the concept of atoms?
Democritus and Leucippos
What lead to the discovery of many elements and important chemicals like minerals acids?
Alchemy : For about 2000 years people attempts to transmute “base” metals (the cheap ones) in to gold.
What is the Dalton’s atomic theory? (6 answers)
- Each element is made up of tiny particles called atoms
- The atoms of a given element are identical
- Chemical compounds are formed when atoms combine with each other.
- A given compound always has the same relative numbers and types of atoms
- Chemical reactions involve reorganization of that atoms – changes in the way they are combined.
- The atoms themselves are not changed in a chemical reaction
What was Dalton’s mistake in classifying atomic masses?
he assumed that the formula of water was HO, so he introduced many errors in his list of atomic masses where he was out by a factor of 2.
Who recognized the static electricity?
Benjamin Franklin
Who discovered that uranium gave off invisible radiation that could fog a piece of photographic film through black paper?
Henri Becquerel
Who first isolated radium and polonium in 1898 and what the person suggest?
Marie Curie
She suggested they were emitting this radiation as the elements decayed to form other elements
The radiation can be analysed and shown to contain 3 components. What are these components?
Alpha particles (α) Beta particles (β) Gamma rays (γ)
The properties of electron were established by two main experiments. The first one was held by J.J. Thomson. What was his experiment?
Cathode Rays: the charge on the plates and the magnetic field strength were adjusted so that the electron beam did not deviate from a straight line. Some relatively simple calculations enable Thomson to calculate the ration of the charge to the mass of the electron
The properties of electron were established by two main experiments. The second one was held by Millikan. What he established and how he established it?
He established the charge and mass of the electron.
Millikan measured the charge on a number of oil drops and took the smallest difference as the charge on the electron
e= -1.60 X 10^ -19 c
Who designed an experiment to probe the interior of an atom?
Ernest Rutherford
How Ernest Rutherford designed an experiment to probe the interior of an atom?
A bean of a particles was directed at a thin gold foil to investigate how it would be scattered.
What are the properties of subatomic particles ?
for the answer see: https://lh3.googleusercontent.com/-Ehum7bfQQno/VMtXXFTTUpI/AAAAAAAABZQ/Zcjg_CSANQo/w800-h800/p-n-e-data.jpg
Atoms are made of
- Electrically _______ protons
- Electrically _______ electrons
- Electrically _______ neutrons
Negative, neutral or positive
protons: positive
electrons: negative
neutrons: neutral
What surround the nucleus
the electrons
The number of __________ is equal to the number of protons.
electrons
The atomic number gives_______________
the number of protons in the nucleus
What is the atomic mass unit (u) ?
one atomic mass unit = 1/12 of the mass of an atom of carbon with 6 protons and 6 neutrons
What information gives the mass number?
the sum of the number of protons and neutrons of an atom
What is a cation?
It’s an atom that losses an electron or electrons and it becomes positively charged
what is an anion?
It’s an atom that gains an electron or electrons and it becomes negatively charged
What is an isotope?
it’s atoms with the same atomic number but different mass number
Isotope: all atoms of the element have the same number of ____________
protons
To have different masses, isotopes must have different numbers of __________
neutrons
how do we calculate the isotopic percent abundance?
(# of atoms of a given isotope) / (total # of atoms of all isotopes of that element) x100
By which process we determine the atomic mass and the isotopic abundance?
experimentally by mass spectrometry
What are groups in the periodic table? What is Group A and Group B
vertical columns
element with similar chemical and physical properties
-Group A: Main group element
-Group B: Transition elements
What are periods in the periodic table?
- Horizontal groups
- Numbered 1 to 7
Periodic table: characteristics of Metals? Differences in mercury and gallium. (6 answers + 2 for mercury and gallium)
o At room temperature they are solids o Conduct electricity o Usually ductile o Malleable o Can form allows o The main group metals are quite soft and reactive o Only mercury (Hg) is liquid o On warm day Gallium (Ga) is liquid
Periodic table: characteristics of Non-metals?
They do not conduct electricity except carbon in the form of graphite
Periodic table: which non-metals are in solid state? (4 elements)
-Carbon (C)
-Sulphur (S)
-Phosphorus (P)
-Iodine (I)
Periodic table: which non-metals are in liquid state? (1 element)
bromine
Periodic table: which non-metals are in gaseous state? (10 elements)
-Hydrogen (H) -Oxygen (O) -Nitrogen -Fluorine (F) -Chlorine (Cl) -Helium (He) -Neon (Ne) -Argon (Ar) -Krypton (Kr) -Xenon (Xe)
Periodic table: characteristics of metalloids?
element that have some physical characteristics of some metal but have chemical characteristic of a non-metal
Give the name of each group: Group 1A: Alkali metals Group 2A: Group 3A: Group 4A: Group 5A: Group 6A: Group 7A: Group 8A: Group 1B to 8B:
Group 1A: Alkali metals Group 2A: alkaline earth metals Group 3A: Boron group Group 4A: Carbon group Group 5A:Pnictogènes Group 6A:Chalcogens Group 7A: Halongens Group 8A: Noble gases Group 1B to 8B: Transitional element
What are the characteristics of the lanthanides?
rare earth element
They are characterized by having very similar physical and chemical properties which make them difficult to separate
What are the characteristics of the actinides?
- All are radioactive
- Some with very short half-lives
- Only miniscule quantities can be made
What is a molecule?
a molecule is the smallest identifiable unit into which some pure substance can be
• divided
• sill retain the composition
• still retain chemical properties of the substance
What is a compound?
It’s pure substance made of more than a single element
What are the 3 types of compounds?
- molecular
- polymeric
- metal and ionic
What is a molecular compound?
- A molecular compound is formed of discrete molecules (discrete = that can be identified and separated without braking the compound).
- The bonding is covalent. Examples: H2O, HCl, O2
What is a polymeric compound?
-No discrete molecules can be identified. They contain covalent bonding that extend to billions of atoms.
-Example: plastics
What is a metal and ionic compound?
-They contain metallic or ionic bonding that extend to billions of ions.
Example: in solid NaCl: each Na+ binds to six Cl- ion, and each Cl- ion binds to six Na+ ion.
-No discrete molecules can be identified.
What is the electronegativity?
“Electronegativity” is the ability of an atom in a molecule or in a polyatomic ion to attract shared electrons to itself.
What are the 3 bonding types?
Ionic
covalent
molecular
What are the characteristics of an ionic bonding?
Between metals and non-metals
- Metal atoms lose electron ex: Na+ (cation)
- Non-metal atoms gain electron ex:Cl- (anion)
- electrostatic attraction between cations and anions form the ionic bonding
- only in the solid state or liquid state
What are the characteristics of an covalent bonding?
Between two non-metals
Sharing of electrons between atoms for the covalent bond
What are the characteristics of a molecular bonding?
Between metal atoms, only in the solid state or liquid state. Metal atoms lose electrons, which are delocalized over the whole sample and highly mobile, making metals excellent electrical conductors and heat conductors [Not studied in this course]
Which information a molecular formula does not provide?
structural information
Which information a condensed formula provide?
Show how the atoms are grouped together
Ionic compounds consist of …………….. (3 things)
- ions
- atoms
- group of atoms
How do we know if an atom will gain or loose electron(s)?
- metals: lose electrons
* non metals: fain electrons
Who made a law based on electrostatic forces ?
Coulomb
how can we calculate the force of attraction?
k ((n^+ e)(n^- e)) / d^2
- K=proportionality constant
- n+ and n-= charge on ions
- e=charge on electron
- d2= distance between ions
Based on Coulomb’s law, the force of attraction between oppositively charges ions increases as the…….
ion charges (n+ and n-) increases
In a monatomic cation, element of Group 1A will loose or gain electron(s)? How many?
loose 1 electron (1+)
In a monatomic cation, element of Group 2A will loose or gain electron(s)? How many?
loose 2 electrons (2+)
In a monatomic cation, element of Group 3A will loose or gain electron(s)? How many?
loose 3 electrons (3+)
What is the ionic charge of Tin and Lead?
2+
What is the ionic charge of Bismuth?
3+
Give the 2 general observations concerning the formation of anions from non-metals. (Monatomic anion)
- Element of Group 5A-6A-7A is the group number minus 8.
- The # of electrons on the anion is the same as the # of electrons in an tom of the noble gas that follow in the periodic table.
hydrogen is a cation or an anion?
both. H+ and H-
In naming ions what are the rules for cations?
- The name is that of the metal + the word “cation”.
- transition elements: name of the element + roman # + cation. ex: cobalt (II) cation
In naming ions what are the rules for monatomic anions?
named by adding –ide
ex: fluoride
In naming ions what are the rules for polyatomic anions?
- Name the cation first, then the anion
* The rules for the metal cation naming are the same
Give the name of the 8 most common anions.
SO3^2- :sulphite SO4^2- :sulphate NO2^- :nitrite NO3^- :nitrate ClO^- :hypochlorite ClO2^- :Chlorite ClO3^- :Chlorate ClO4^- :perchlorate
What are the rues in naming ionic compounds?
- built from the name of the positive and negative ions in the compound
- the name of the positive cation is given 1st
- –The name is that of the metal + the word “cation”.
- –Transition elements: name of the element + roman # + cation. ex: cobalt (II) cation
- followed by the name of the negative anion
What is a binary molecular compound?
It’s a combination of 2 non-metals.
How the formula of a molecular compound is written?
The elements are putted in order of increasing group number.
State the 5 more common molecular compound?
o NH3: ammonia o N2H4: hydrazine o NO: nitric oxide o N20: nitrous oxide o H20: water
Hydrogen forms molecular compounds with most ______________ except the _____________.
Hydrogen forms molecular compounds with most NON-METALS except the NOBLE GASES.
How do we name an hydrogen compound with an element of group 6A/7A?
The word hydrogen is named first, and then the other element designated as if it were and anion.
State the 6 important molecular compound.
CH4:methane SiH4: silane GeH4: germane PH3:phosphine AsH3: arsine SbH3: stibine
What are the rules in naming binary molecular compound?
- The first element is given its normal name
- The second element is named as if it were an anion
- Prefixes are used to designate the number of atoms
What is the unit for measuring an amount of a substance?
The mole
What is the definition of the mole?
The mole is the amount of a substance that contains as many elementary entities (atoms, molecules, particles) as there are atoms in exactly 12g of the carbon-12
What is the formula to convert moles to mass?
moles x (grams/1 mol)
What is the formula to convert mass to moles?
grams x (1 mol/grams)
What is the molar mass of one mole of an element?
is the mass of 6.022 X10^23 atoms of that element.
How can we determine the formula of a compound?
- by giving the formula of the compound
- the mass of each element per mole of compound
- the mass of each element in the compound relative the total mass of the compound – that is a mass %
is the oxidation state the same as oxidation number?
yes
which element and group of element have one oxidation number?
Groups 1 to 3 and group 12
Al
Ag,
all lanthanides except Ce and Eu
which element and group of element have several oxidation number?
All main group metals except group 1 to 3 and 12.
transition metals of groups 4-11
Ce and Eu (lanthanides)
all actinides
What is the relation between the ionic bonding and the oxidation number?
number of electrons lost (ON>0) for least electronegative element
number of electrons gained (ON
Do we calculate differently the oxidation number for ionic bonding and covalent bonding?
no, for covalent bonding, oxidation numbers are calculated like if bonding were ionic.
Does oxidation number are predictable for main group element?
yes
What is the oxidation number for Group 1 elements?
+1
What is the oxidation number for hydrogen (H) ?
+1 and when bonded to a metal -1
What is the oxidation number for Group 2 elements?
+2
What is the oxidation number for Group 13 elements?
+1 and +3
What is the oxidation number for Group 14 elements?
+2 and +4
What is the oxidation number for Group 15 elements?
-3, +1, +3, +5
What is the oxidation number for Group 16 elements?
-2, +2, +4, +6
What is the oxidation number for Group 17 elements?
-1, +1, +3, +5, +7
What is the oxidation number for Group 18 elements?
0,+2,+4,+6,+8
What is the oxidation number for Group 3 elements?
+3
What is the oxidation number for Group 7 to 10 elements?
+2
What is the oxidation number for Group 11 elements?
+1
What is the oxidation number for Group 12 elements?
+2
What is the oxidation number for lanthanides elements?
+3
What are hydrated compound?
Compounds in which molecules of water are associated with the compound are called “hydrated compounds.”
