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Kartei Details
Karten | 34 |
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Sprache | English |
Kategorie | Chemie |
Stufe | Mittelschule |
Erstellt / Aktualisiert | 05.04.2022 / 06.04.2022 |
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What is a peridoic table and who did develop it?
It was developed by Dimitri Mendeleev who organised elements bades on increasing molar mass and similar properties, not by atomic number.
What is the periodic law?
The properties of elemtns repeat in pattern on the periodic table when they are organized by increasing atomic mass.
What is a period?
horizontal row on periodic table. Elements in a period have the same number of shells (energy levels).
What is a group/family?
vertical columns on peridoic table. Elements within a group have similar properties, numbers on top of the periodic table indicate the group #.
What are the main group?
the eight "tallest" columns on the periodic table, groups 1,2 & 13-18
What are the transition metals?
groups 3-12, have greater complexity in electron configuration, many of these can form more than one type of ion
list the properties of metals
- hight melting points (all execpt mercury are solid at room temperature)
- shiny when freshly cut or polished
- malleable (dehnbar) -> can pushed into a sheet
- ductile (plastisch verformbar) -> can be pulled into thin water
- generally flexible as thin sheets or wires
- good conductors of heat and elctricity
- tend to lose electrons and form positive ions when reacting
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list the properties of non-metals
- lower melting points
- solids are not malleable, ductile or flexible
- poor conductors of heat and electricity
- tend to gain electorns and form negative ions when reacting or will share electrons when reacting with other non-metals
list the properties of metalloids
- have a blend of properties of metals and non-metals
- most are partial electrical conductors at room temperature
What are valence electrons?
electrons in the outer most level/shell
What does determine the chemical properties?
the number of valence electrons
What is the name of the first group? What properties do they have?
it has the name akali metals.
- soft, silvery solids
- the most reactive of all metals
- corrode rapidly in air to a dull gray
- readily form compounds with non-metals, the resulting compounds are highly soluble in water.
- have one valance electron
- lose 1 electron to make ions with one positive charge
- react vigorously with water to produce hydrogen gas
What is the name of the second group and what properties do they have?
They have the name Alkaline Earth Metals.
- silvery solids, harder than alkali metals
- corrode more slowly in air to a dull gray
- react with water to produce hydrogen gas (not as vigourously as alkali metals)
- form compounds with non-metals, the resulting compounds often have lower solubility in water
- form compounds with non-metals, the resulting compounds often have lower solubility in water
- have 2 valence electrons
- lose two electrons to make ions with a two charge
What is the name of the group 17? What properties do they have?
They have the name halogens.
- very reactive non-metals with 7 valence electrons
- gain one electron
What is the name of group 18?
It has the name noble gases.
- non-reactive, full outer shells
- do not gain or lose electrons
What is isoelectronic?
ions and elements with the same electron configuration (these will have the same number of electrons)
What is the atomic radius?
the size of an ato from the centre of the nucleus to the outermost energy level
Why does the atomic radius decreases in a period?
going across a period, atoms have the same number of energy levels but more electrons and protons which increases the attraction between the nucleus and the electrons, causing the outer shell/level to be pulled in and thus the radius decreases
Why does the atomic radius increase in a family?
going down a family, each new period represents a new shell added further away from the nucelus, each new energy level increases the radius
What is ionization energy?
energy required (erforderlich) to remove an electron from a neutral atom
the stronger an electron is attracted to the nucleus the greater....
the ionization energy, as radius decreases (increasing electron-proton attractiom), ionization energy increases
What is electronegativity?
the ability of an atom to attract a bonding electron
What is the metallic character?
metals tend to lose electrons, non metals tend to gain electrons, elements with a stronger tendency to lose electrons are considered more metallic
Why bond?
- only noble gas atoms have full outer electrons shell, this is the most stable arrangement
- when atoms react, they either lose, gain or share electrons in a way that allows them to have full outer electrons shells, gaining stability
What types of bonds exist?
- ionic bond
- pure covalent bonds
- polar covalent bonds
When do atoms doing a ionic bond?
They do it when they have extremely different electronegativity.
What is a ionic bond?
the attraction between oppositely charged ions is called an ionic bond.
When do atoms do a pure covalent bond?
They do it when both atoms have high electronegativity, so both atoms want to attract an electron, but neither atom can take electrons from the other atom
What is a covalent bond?
a bond created when to atoms which hold their electrons strongely (non-metals) share a pair of electrons.
What is a pure covalent bond?
if both atoms have very similar electronegativities, electrons are shared equally between atoms creating a bond with no electrical charge
When do atoms do a polar covalent bond?
if both atoms have electronegativities that are significantly different but not different enough to create an ionic bond, electrons are shared unequally between the atoms
What does an unequal sharing mean?
the more electronegative atom pulls the electrons closer, this atom becomes negative
this create a bond with one slightly negative end and one slightely positive end
these negativee and positive poles make a dipole
What is polar covalent?
a covalent bond with a dipole
can a molecule have a polar covalent bond and be non-polar?
yes, it depends on the symmetry