Unit 2 - atoms, elements and compounds Flashcards
1
Q
Element
A
A substance that can’t be broken down into anything simpler using a chemical reaction - only have 1 type of atom and each is unique
2
Q
Compound
A
Formed when one or more atoms of different elements are joined together by chemical reactions
3
Q
Mixture
A
Formed when two or more substances are found together but not chemically bonded to each other - can be elements or compounds - can be easily separated
4
Q
Three sub-atomic particles in atoms
A
- Electrons
- Neutrons
- Protons
5
Q
Location of sub-atomic particles
A
- Electrons - energy shells
- Neutrons - in the nucleus
- Protons - in the nucleus
6
Q
The nucleus of an atom
A
- Radius of the nucleus is 10000x smaller than radius of the atom
- Most of the mass is within the nucleus because protons and neutrons have the most mass
7
Q
Protons
A
- Number of protons = proton/atomic number
- Number of protons determines the element
- Mass of 1
- Charge of +1
8
Q
Neutrons
A
- Mass of 1
- Charge of 0
- Atoms of the same element but different amount of neutrons are isotopes
9
Q
Electrons
A
- Smallest sub-atomic particle
- Mass of 1/2000
- Charge of -1
- Orbit the nucleus in shells
- Number of electrons = number of protons - elements have no charge
10
Q
Features of elements on the periodic table
A
- Nucleon/atomic mass number
- Proton/atomic number
11
Q
Atomic number
A
- Also known as proton number
- Number of protons in an element
- Shows amount of electrons in the element too
12
Q
Atomic mass Number
A
- Also known as nucleon number
- Number of protons + number of neutrons
13
Q
Neutron calculation
A
Atomic mass number - Proton number
14
Q
Electronic configuration
A
The distribution of electrons of an atom or molecule in electron shells
15
Q
Amount of electrons in each shell
A
- First shell = Max of 2
- Second shell = Max of 8
- Third shell = Max of 8
- Fourth shell = Max of 18
- …
16
Q
How to write electron configuration
A
- Written in the form x,x,x,
- Example - Aluminum = 2,8,3
17
Q
Elements that have full shells and are uncreative
A
Noble gases - Group VIII
18
Q
Ions
A
Charged atoms
19
Q
What elements have to do to become stable
A
- Obtain a full outer shell through losing or gaining electrons
20
Q
Ion charges of elements in each group
A
- Group 1 = 1+
- Group 2 = 2+
- Group 3 = 3+
- Group 4 = 4+-
- Group 5 = 3-
- Group 6 = 2-
- Group 7 = 1-
- Group 8 = 0
21
Q
Isotopes
A
Atoms with the same number of protons but different numbers of neutrons
22
Q
Nuclear notation
A
- Mass number on upper-left
- Atomic number on lower-left
- Chemical symbol on the right
- If ion, charge is on upper-right of chemical symbol
23
Q
Calculating average relative atomic mass
A
- Average Atomic mass = Sum of [(Atomic mass x % abundance)] for each isotope ÷ 100
- Average Atomic mass = sum of [(atomic mass x relative abundance)] for each isotope ÷ sum of the relative abundance
24
Q
Ionic bonding
A
Occurs between metal and non-metal atoms - metal donates electrons to the non-metal for both to obtain full shells
25
Cations
- Positive ions
- Donate electrons in bonding
- Metal atoms in ionic bonding
26
Diagram used for ionic bonding
Dot-and-cross diagram
27
Anions
- Negative ions
- Gain electrons in bonding
- Non-metal atoms in ionic bonding
28
Suffix for non-metals in ionic bonding
- ide e.g. fluorine --> fluoride
29
Forces keeping together ionic bonds
Strong electrostatic forces between positive and negative charged particles
30
Structure made from ionic bonding
- Giant lattice structure held together by strong electrostatic forces of attraction
31
Ionic bonding with incomplete electrons
- If one element can't donate enough electrons, multiple of the element will be used e.g. lithium and oxygen
32
Properties of ionic compounds
- High melting and boiling points - Higher if there is higher charge since more energy is needed to break bonds and separate ions
- Conduct electricity molten or dissolved in water to make aqueous solutions, not as solid - ions can freely move molten or dissolved but not as a solid
32
Covalent bonds
A bond between two non-metals through the sharing of electrons
33
Rules of covalent bonding
- Both atoms involved must share the same number of electrons
- The number of electrons shared os qual to the number of electrons needed to fill the outer shell
- The smallest number of electrons needed are shared
34
Types of covalent bonds
- 1 pair of electrons bonding = single bond
- 2 pairs of electrons bonding = double bond
- ...
35
Diagram used for covalent bonding
Dot-and-Cross diagram
36
Properties of covalent bonds
- Low melting point - for simple covalent molecules - large molecules need more energy and have higher melting points
- Don't conduct electricity - don't have charged particles that can move through the structure
37
Composition of diamond
- Made of only carbon
- Each carbon shares one electron with four other carbons to make a giant structure
- Known as a macromolecule
- Very hard - due to strong covalent bonds in giant structure
- Used for cutting tools
38
Composition of graphite
- Made of only carbon
- Each carbon shares one electron with three other carbons, fourth is delocalized
- Known as a macromolecule
- Layered hexagonal arrangement held together by weak intermolecular forces - lets layers slide
39
Uses of graphite
- Powder can be added to surfaces of moving parts e.g. engine parts to reduce friction
- Used as electrodes in a battery
- Electrical contacts in motors
- Electrodes in electrolysis
40
Composition of Silicon(IV) oxide
- Each silicon shares an electron with 4 oxygens - forms 4 covalent bonds
- Each oxygen makes two bonds with silicon atoms
41
Properties of Silicon(IV) oxide
- Forms transparent crystals
- Very hard - less than Diamond
- Extremely high melting and boiling points
- Do not conduct electricity - no delocalized electrons
- Do not dissolve in water
42
Metallic bonding
Electrons form a 'sea' of delocalized electrons that surround positive metal ions - held together by strong electrostatic forces of attraction - form giant metal lattice structure
43
Properties of metals
- High melting and boiling points - lots of energy needed to break the bonds of the lattice
- Conduct electricity - due to presence of delocalized electrons
- Malleable - layers which can move and slide past each other
- Ductile - layers can move and slide past each other
