Chemistry Flashcards
what is sedimentation?
the process in which solids settle to the bottom of a container.
What is sieving?
Separating solid particles according to particle size by passing through a perforated barrier.
What is distillation?
The process of separating the liquid component of a solution by boiling the solution and condensing the resulting vapor back to a liquid.
What is decantation?
the process of carefully pouring off the liquid and leaving the solid undisturbed at the bottom of the container.
What is filtration?
The process of separating undissolved solid from a liquid by passing the mixture through a filter.
What is magnetic separation?
The process of passing a mixture through a magnetic field to separate the magnetic and non-magnetic components.
What is evaporation?
The process of separating dissolved solid from a solution by vaporising the liquid.
What is crystallisation?
The process of forming crystals from a solution.
What properties do we use when separating particles of different size?
sieving
What properties do we use when separating solids from liquids?
Filtration, decantation.
What properties do we use when separating dissolved solids from liquid?
Evaporation or crystallisation
What physical properties do we use when separating two or more liquids?
Distillation
What physical properties do we use when separating immiscible (don’t dissolve in one another) liquids?
Separating funnel.
Work done by John Dalton?
- 1804, proposed that tiny particles called atoms were the fundamental particles of nature.
- His theory was that atoms of elements were solid and indivisible.
Who did work to discover established that atoms consist of protons neutrons and electrons?
Thompson (plum pudding model), Rutherford and Bohr.
About the nucleus of an atom:
- Positively charged
- Contains protons and neutrons.
- Electrons are negatively charged.
How are atoms electrically charged?
Neutral.
Proton- mass, relative mass and relative charge
1.673 x 10^-27
1
+1
Neutron- mass, relative mass, relative charge.
1.673x10^-27
1
0
Electron- mass, relative mass and relative charge
9.11x10^-31
0
1
What does the atomic number illustrate about the atom?
The number of protons in the nucleus.
What is the mass number?
The total number of protons and neutrons.
What are isotopes?
Isotopes are different forms of an element. All the atoms of a given element have the same number of protons but the number of neutrons may vary. Different forms of an element may have a different mass number.
What is an element?
Elements are substances that contain only one type of atom.
What are compounds?
Compounds contain two or more elements, joined together by chemical bonds.
What differs compounds from elements?
Compounds have properties which are different from the element they contain.
What is the periodic law?
The properties of the elements are a periodic function of their relative atomic masses.
How is the modern periodic table assembled?
The elements are in strict order of their atomic numbers. It is divided into vertical groups of similar elements and five blocks of elements with similar properties.
What causes elements to have similar properties?
Electrons, the valence electrons.
What is the letter order of the orbitals?
1s, 2s 2p, 3s 3p 3d, 4s
What is the exception to the letters of the orbitals?
The 4s shell must be filled before filling the 3d shell.
How many electrons can each letter orbital have?
s-2
p-6
d-10
How do elements become noble gases?
Metals tend to LOSE electrons to attain a noble gas configuration, whereas non-metals tend to GAIN ELECTRONS. The noble gases neither lose nor gain electrons because THEY ARE STABLE WITH A FILLED SHELL.
What two elements are an exception to the orbital rule, with their 3d shell being filled or half-filled before their 4s?
Chromium and Copper
What is a bond?
The electrostatic force that holds atoms, ions or molecules together.
How is the type of bond between atoms determined?
The type of bond that exists between atoms depends on the electron configuration.
How are bonds formed?
Formed by the behavior of VALENCE ELECTRONS
What are the three sorts of bonds?
- Ionic
- Covalent-molecular or network
- Metallic
What is ionic bonding?
Bonding between metals and non-metals.
What is electronegativity?
A measure if how well an atom can attract electrons
Why can metals and non-metals ionically bond?
Because metal atoms have a low number of valence electrons and a low electronegativity. Non-metal atoms have numerous valence electrons.
How do metals behave during ionic bonding?
- Lose valence electrons
- Achieve a stable valence shell (usually 8e-)
- Gains a positive charge, cation or positive ion.
How do non-metals behave during ionic bonding?
- Gain valence electrons
- Achieve a stable valence shell
- Gains a negative charge - anion or negative ion.
What is the ionic lattice?
- Positive and negative ions attract each other to form a three dimensional continuous lattice structure.
- The ratio of cations to anions in the lattice is determined by the charges of the ions.
Name the seven radicals:
NO3- Nitrate OH- Hydroxide SO4 2- Sulfate CO3 2- Carbonate PO4 3- Phosphorus HCO3- Hydrogen Carbonate NH4+ Ammonium
State the following properties of ionic compounds: Melting and boiling points: Electrical Conductivity: Hardness: Brittleness:
- High because large amount of thermal energy required to separate ions which are bound by strong electrostatic forces.
- Solids do not conduct electricity, no mobile charged particles. When molten and in solution, ions are able to carry electric charge and conduct electricity.
- Most are hard, not easily scratched, aren’t easily displaced
- Most are brittle, will shatter
What is Covalent Molecular bonding?
Bonding between two non-metals. All atoms have fairly high electronegativity and few vacancies in valence energy levels. Electrons shared to achieve stable configuration.
State the following properties of covalent molecular compounds:
Melting and boiling points:
Electrical Conductivity:
Hardness:
- Low because molecules become separated with little thermal energy.
- Do not conduct-no mobile charges particles.
- Soft, weakly attracted and easily displaces
What are the prefixes attached to covalent molecular bonds?
1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 septa
How are atoms shared in covalent molecular bonds?
Electron pairs are shared equally between atoms of equal electronegativity.
What is a coordinate covalent bond?
Where two electrons are shared evenly with the other atom.
What happens if atoms in a covalent bond have differing electronegativities?
Electron pairs are attracted closer to the atom with the higher electonegativity value.
What happens to the atoms losing and gaining electrons?
Atom gaining electrons acquires a slight negative charge (delta -ve)
Atom losing electrons acquires a slight positive charge (delta +ve)
The bond is polar
What is covalent network bonding?
Bonding between non-metals, form covalent bonds. Do not form separate molecules but a continuous network
State the following properties of covalent network compounds:
Melting and boiling points:
Electrical Conductivity:
Hardness:
- Very high melting point, each atom bound by strong covalent bond
- Poor conductor, electrons cannot move through the lattice (except graphite) approx. 3000
- Hard
What is a metallic bond?
- Transition metals
- The interaction that holds metal atoms in one piece.
- Characterised by low ionistion energy
What is ionisation energy?
The energy required to remove the most loosely held electron from an atom in the gaseous phase.
State the properties of metallic compounds:
- dense (heavy)
- high melting and boiling points
- Good conductors of heat and electricity
- Malleable and ductile (bendy)
- Lustrous (shiny)
What is the test for carbon dioxide?
turn lime water milky
What is the test for hydrogen?
Squeaky pop
What is melting point related to?
The electrostatic attraction in the bonds.
