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