2 - Atoms, Elements & Compounds Flashcards
Describe the features of Graphite
Made from Carbon
- made from layers of carbon atoms
- atoms arranged in hexagons
- strong covalent bonds between carbon atoms
- weak intermolecular forces between layers
- 3 covalent bonds, 1 delocalised electron
- only nonmetal > good conductor of electricity
-layers slide
Uses :
- pencils
- lubricants
Name the types of physical property:
White -
Solid -
801°-
2.17 g/m3 -
1413° -
Soluble in water -
Crystalline -
- Colour
- state (at room temperature)
- melting point
- Density
- boiling point
- solubility
- structure/ appearance
How are electrons distributed in non-water molecules
Randomly,
but there is always a place with more electrons than the other, creating + and - charges, and intermolecular forces
What is water’s special property regarding electrons?
Electrons NOT evenly distributed
Oxygen attracts more electrons from Hydrogen
Give an example and a non-example of “isotope”
H-1, H-2, H-3
__________________________
He is Not isotope of hydrogen
Define Particle
- Building blocks of the universe
- Portion of matter
Def. nucleus
The centre of the atom, composed of protons and neutrons.
Def. electron shell
Orbits of electrons circling the nucleus
Def. electron
A particle in the atom with a negative charge and relative mass of 0, that orbits the nucleus in electon shells.
Def. proton
Positively charged particle in the nucleus of an atom
Def. neutron
Neutrally charged particle in the nucleus of an atom
What are the relative charges and masses?
Proton
Electron
Neutron
Proton - +1,1
Electron - -1, 0
Neutron - 0,1
Name the first 4 shells and the amount of electrons they contain
1st shell - 2
2nd shell - 8
3rd shell - 8
4th shell - 8
Up to atom 20
Give another word for “atomic number”
What is it ?
Proton number
(number of protons)
(meaning also electrons)
Give another word for “relative atomic mass”
What is it?
Nucleon number
(protons + neutrons)
What is an isotope?
Atoms of an element with the same number of protons and electrons,
but a different number of neutrons
What is a covalent bond?
An electrostatic attraction between shared electrons and adjacent nuclei
(see paper card for diagram )
What are the characteristics of an ionic compound
- Casually contain a metal + one or two non-metal
- The solid is an ionic lattice
Give example and non example of molecular substances
- Oxygen O2, Sulfur S2, Hydrogen H2
- Water H2O, Methane CH4, Carbon dioxide CO2
________________________________
non-examples : - ionic compounds like MgO or NaCl
- Giant covalent structures like diamond
- metals like sodium or copper
Why is a nitrogen molecule un-reactive?
Because it has more bonds, making it more stable
N=_N
Why do molecular solids melt easily?
Weak intermolecular forces
Why are most substances made from molecules liquids or gases at room temp.?
EMPTY
Why are molecular substances ALWAYS poor conductors of electricity? Except for graphite.
EMPTY
What does N2 look like
7
N, 2, 5
14
Nitrogen sharing 3 covalent bonds with other Nitrogen
What happens to inter molecular forces as a gas
They are still there, but molecules have energy to break free
What is electron configuration of
3
Li+
7
2
Define “ionic lattice”
A solid formed from cations and anions held together by an ionic bond
Define “ionic bond”
Electrostatic attraction between oppositely charged ions
Define Lattice
regular arrangement
Al (OH)3 Why brackets?
To not confuse between Al + O + 3 x H and Al + O x H x 3
Name the compound NaI
Sodium iodide
Name the compound AlPO4
Aluminium phosphate
Name Li3N
Lithium nitride
What are there
O=O
H-H
N=_N
Molecules of :
Oxygen
Hydrogen
Nitrogen
What is electronic configuration? how many protons, neutrons, electrons?
8
O
oxygen
16
8,8,8
2.6
11p 2.8,1 18p 2.8.7
10e 17e
What happens?
reaction
11p 17p
10e 2.8 — +1 —> 18e 2.8.8
Cation anion
full outer shells!
(to be balanced)
What do you call a positive ion?
Cation +
What do you call a negative ion?
Anion -
What would a reaction between chlorine and sodium create?
NaCl
Sodium Chloride
What a the characteristics of isotopes?
- Atomic number does not change
- Relative atomic mass can change
- electron configuration same
- isotopes have same properties as each other except for mass
What is a polyatomic ion?
Ion composed of multiple elements
e.g. SO4, sulphate
What is the ratio of cations to anions in NaCl?
1:1
What is an electronic configuration?
A way to represent number of electrons in each shell
e.g. 2,8,3 (Aluminium)
What is electron valency?
Outer shell
What are the patterns in the periodic table?
noble gases = full shell
Otherwise, group number = n. of electrons on outer shell
period number = n. of electron shells
Always increasing by 1 proton
Name the parts of an atom
nucleus, electron, neutron, electron shell, proton
12
Mg (78,70%) found in nature
24
12
Mg (10.13%)
25
12
Mg (11.17%)
26
Find Ar
(78.7x24) + (10.13x25)
+ (26x11.17)
_____________________________
100 (because per cent)
17
Cl How to find Ar?
35.5
25Cl 25Cl
25Cl 27Cl
Find mean average
(25)3 + 27
______________ = 35.5
4
What is overall charge ?
16p
17e
-1
How would they react?
Ca F 2.8.8.2 2.7
Ca gives one electron each to 2 F atoms
What does Ar stand for?
Average relative atomic mass
What happens when you try to conduct electricity through a liquid ionic substance
The ions transfer electricity by moving towards the electrodes
Def. Atom
A neutral particle composed of protons, neutrons, and electrons
Define ion
A particle with a positive or negative charge due to the loss or gain of electrons
Define and draw a molecule
Two or more atoms joined together by covalent bonds (and it is neutral)
easter egg!
Coucou! :-)
How many covalent bonds does carbon make
Alway 4
What is simple covalent bonding VS Giant covalent bonding
- set number of atoms bond
- can have infinite amount of bonds
Did you know which atom has an anomaly in non-metal ion names?
Carbon
Carbide
Carbonate
? +? = 2NaCl
2Na + Cl2 = 2NaCl
What are the physical properties of ionically bonded substances ?
- high melting point
- conductive when dissolved/ liquid/ gas
when ions can move
Highlight differences : molecular vs macromolecular
- made of small molecules joined by weak intermolecular forces
- atoms joined with strong covalent bonds
_____________________________
One giant molecule in which ALL atoms are joined together with strong covalent bonds
What does immiscible mean?
Can’t mix
e.g. oil and water don’t mix
What is NH3?
Ammonia
Def. intermolecular forces
Forces (electrostatic attractions) between molecules (weak, easy to break)
Def. molecular substances
A substance made from molecules that could be a solid, liquid or gas at room temperature
What are the general properties of simple covalent molecules?
Normally:
- electrical insulator
- low melting point
- gas at room temperature
Why is diamond hard ?
Why is graphite soft?
Graphite good conductor of electricity?
EMPTY
Describe the features of silicon dioxide
- aka: sand, quartz
- SiO2 simplest ratio of each element (1:2)
- very high melting point - about 1500°
- 3D lattice of atoms
- each silicon makes 4 strong covalent bonds, oxygen makes 2
- when pure-> transparent
- uses: glass
What are the features of diamond
- Made from carbon atoms
- each carbon 4 bonds
- 3D lattice of atoms
- Transparent
- extremely hard, almost impossible to scratch
- melting point 4000°
- uses : jewellery, drilling (and cutting glass btw)
Def. Element
Substance made of only one type of atom
Def. Compound
Substance made of 2 or more elements chemically bonded.
It has a definite composition (you can wite a formula)
Def. Mixture
Substance made of 2 or more substances physically combined.
It has a variable composition (you cannot write a formula)
Def. Solution
A mixtrue of one r more dissolved solids (solutes) in to a liquid (solvent)
Def. Solvent
The larger component of a liquid mixture, a substance that dissolves a solute
Def. Solute
The smaller component of a lquid mixture, a substance dissolved into into a solvent.
Def. Saturated solution
A solution containing the maximum concentration of a solute dissolved in a solvent at a specifiesd temperature.
Def. Residue
The particles left behind in a filter
Def. Filtrate
The particles that came through a filter
Suggest a method to separate mixed salt and pepper
- Add water to the mixture
- Stir and dissolve the salt into a solution (pepper is insoluble)
- Pass the mixture through a filter to separate the salt solution from the pepper
- Boil the salt solution to get rid of the water
What is a solute
something dissolved in water
What are characteristics of molecular substances
- non-metal atoms that join together with covalent bonds to form molecules
(share electron —> full outer shells) - molecules attracted to each other by weak intermolecular forces
- Volatile (turn to gases easily)
- often soluble (in water or other solvent like alcohol)
- poor conductors of electricity in any form
What are the state symbols ?
g = gas
l = liquids
s = solids
aq = aqueous : dissolved in H2O
Def. Periodic Table
An arrangement of elements in periods and groups and in order of increasing proton number/atomic number
Describe the change from metallic to non-metallic character across a period
Decreases as you move left to right (down a period), while Increases as you go down groups
Def. Metal
Elements that will form positive ions when they react because they lose electrons.
Def. Nonmetal
Elements that will form negative ions when they react because they gain electrons.
Def. Semimetals/Metalloids
Elements that display characteristics of both metals and nonmetals
Def. Metallic character
Level of reactivity of a metal
Def. Nonmetallic character
Tendency to accept electrons during chemical reactions
Describe the relationship between group number and the charge of the ions formed from elements in that group
The group number is equal to the number of electrons in the outer shell, which dictates what kind of ion the atom will form when it reacts. A group 1 ion wil have +1 charge, and a group 2 ion will have a +2 charge, and so on. From group 5 onwards, the charges are -3, -2, and so on.
Compare the thermal conductivity of metals and nonmetals
Metals are good conductors of heat, while non metals are insulators of heat
Compare the electrical conductivity of metals and nonmetals
Metals are good conductors of electricity, while non metals are insulators of electricity
Compare the malleability and ductility of metals and nonmetals
Metals are malleable and ductile while nonmetals are brittle
Compare the melting and boiling points of metals and nonmetals
Metals have higher melting and boiling points than nonmetals
Describe the properties of noble gases
- Unreactive,
- Monatomic
- Gas
Explain why noble gases are unreactive in the terms of electronic configuration
Noble gases have full outer shells so they are stable. This means they do not need to gain or lose lelectons to increase their stability.
So all other atoms react to get noble gas-like, full outer shells
What happens in metallic bonding?
Each metal electron in the outer shell becomes delocalised form the atom, leaving a cation. The electrons can move freely between different ions, forming a sea of delocalised electrons.
Why is there a strong electrostatic attraction in metallic bonds?
The negative delocalised electrons are attracted to the positive metal ions.
How many electrons are there in a sea of electrons in a metallically bonded substance?
A number equal to the amount of positive charges of the cations
So the overall charge its neutral
