Science Flashcards
(87 cards)
1
Q
What is an Atom?
A
Atoms are the basic building block of all matter
2
Q
What is a scanning tunnelling microscope used for?
A
A scanning tunnelling microscope is used to see atoms
3
Q
What is the centre of the Atomic Structure called?
A
The Centre of the Atomic Structure is called the nucleus
4
Q
What does the Nucleus contains?
A
The Nucleus contains protons and neutrons.
5
Q
What are Molecules and Crystal Lattices?
A
If two or more aroms (all the same different) bond together they form a molecule or a large grid-like structure called a crystal lattice
6
Q
What moves around at high speed in the nucleus?
A
Electrons move around at high speed in the nucleus.
7
Q
How does subatomic particles work?
A
Electrons and protons are oppositely charged, electrons are attracted to the nucleus (protons) and so are held in their clouds around the nucleus
8
Q
What is an element?
A
Elements are substances made up of one type of atom only.
9
Q
What are some examples of Molecules and Crystal Lattices?
A
Some examples of Molecules and Crystal Lattices are:
- Water
- Silicon dioxide
10
Q
What is an Compound?
A
If a molecule or crystal lattice is made up of two or more different types of atoms it is called a compound.
11
Q
What are some examples of componds?
A
Some examples of compunds are:
- Salt
- Sugar
12
Q
How many element are there in periodic table?
A
there are 118 element in the perodic table.
13
Q
How is the Periodic table arranged?
A
They are arranged in order of the increasing Atomic Number.
14
Q
How are the elements on the Periodic Table Classified?
A
They are classified according to their properties as metals, non-metals and metalloids.
15
Q
What are Groups in the Periodic Table?
A
Groups are vertical columns (Groups 1 -18)
16
Q
What is Group 1 on the Periodic Table?
A
Group 1 is Alkali Metals.
17
Q
What is Group 2 on the Periodic Table?
A
Group 2 is Alkali Earth Metals.
18
Q
What is Group 3 to 12 on the Periodic Table?
A
Group 3 to 12 is Transition Metals.
19
Q
What is Group 17 on the Periodic Table?
A
Group 17 is Halogens
20
Q
What is Group 18 on the Periodic Table?
A
Group 18 is Noble Gases.
21
Q
What are Periods on The Periodic Table?
A
Periods are Horizontal rows ( Periods 1 - 7)
22
Q
What are Periods 1 to 7?
A
Periods 1 to 7 are Lanthanides and Actinides
23
Q
What are the Properties of Metals?
A
The Properties of Metals are:
- High melting point
- Conductors of electricity
- Conductors of heat
- Lustrous (shiny)
- Hard
- Ductile (able to be drawn into a wire)
- Malleable (shape can be manipulted)
- Solid at room Temperature (mostly)
24
Q
What are the Properties of Non-metals?
A
- Mostly gases, some solids at room temperature
- Low melting points
- Non-conductors of heat and electricity
- Brittle
- Soft and pliable
25
What are Alkali Metals?
Alkali Metals are:
1. There are Group 1 on the Periodic Table ( expect Hydrogen)
2. Highly reactive metals
3. React with water
26
What are Alkaline Earth Metals?
Alkaline Earth Metals are:
1. They are Group 2 on the Periodic Table
2. Less reactive metals than group 1
27
What are Halogens?
Halogens are:
1. In group 7 on the Periodic Table
2. Highly reactives gasses
28
What are Noble Gasses
Noble Gasses are:
1. Group 8 on the Periodic Table
2. They are Unreactive gasses
29
What are Alloys?
Alloys are:
1. Most metalls around us are not pure metals but are alloys
2. An alloy is a metl (base metal) combined with small amounts of other elements
3. The Properties of the alloy are usually an improvement over those of the base metal e.g. Steel
30
What is the Continuum Model?
The ancient Greeks believed that all matter was made up of only four fundamental elements: earth, fire, air, and water. This was the basis of the continuum model, which predicted that regardless of the number of times you halve a piece of matter, it can always be broken down into even smaller pieces.
31
What is the Solid- Ball Model?
The Greek philosopher Democritus suggested that matter was not continuous but was made up of tiny, solid, and unbreakable particles. He was the first to use the term atomos meaning 'indivisible', from which the word atom comes.
32
What is the Plum Pudding Model?
The 'plum pudding' model of the atom was proposed by JJ Thomson, who had also discovered the electron. It was put forth before the discovery of the nucleus. According to this model, the atom is a sphere of positive charge, and negatively charged electrons are embedded in it to balance the total positive charge.
33
What is the Nuclear Model?
nuclear model, any of several theoretical descriptions of the structure and function of atomic nuclei (the positively charged, dense cores of atoms). Each of the models is based on a plausible analogy that correlates a large amount of information and enables predictions of the properties of nuclei.
34
What is the Planetary Model?
According to the Bohr model, often referred to as a planetary model, the electrons encircle the nucleus of the atom in specific allowable paths called orbits. When the electron is in one of these orbits, its energy is fixed.
35
What is the Electron cloud Model?
The electron cloud model is a model of an atom in which the atom consists of a small but massive nucleus surrounded by a cloud of rapidly moving electrons. The electron cloud model says that we cannot know exactly where an electron is at any given time, but the electrons are more likely to be in specific areas.
36
What is the Atomic Number?
The Atomic Number of an atom is the number of protons in the nucleus. It identifies the element.
37
What is Mass Number?
Mass number is the total number of protons and neutrons in the nucleus of an atom is the mass number.
38
What is Isotopes?
Isotopes are atoms of the same element that have a different number of neutrons.
39
What is the Atomic Notation?
The Atomic Notation shows us the mass number and the atomic number of an atom we write an atomic symbol.
40
How to calcuate numbers of protons, neutrons and electrons?
Example: nitrogen
Atomic number = 7
Mass number = 14
Number of protons = atomic number number of protons in nitrogen = 7
Number of electrons = number of protons (for an atom) number of electrons in nitrogen = 7
Number of neutrons = mass number – number of protons or atomic number
∴ 14 – 7 = 7 neutrons
41
What does the Atomic Notation allow us to do?
It allows us to calculate the number of protons, neutrons and electrons for an atom.
42
How to calculate atomic Number and Mass number?
Example: beryllium
Number of protons = 4
Number of electrons = 4
Number of neutrons = 5
1. Atomic number = number of protons atomic number of beryllium is 4
2. Mass number = number of protons + number of neutrons ∴ mass number of beryllium is 4 + 5 = 9
43
How can you form an ion?
Electrons can be removed or added from an atom to form an ion.
44
What are some example of elements?
Some Examples of elements are:
- Oxygen
- Sulfur
- Buckyball
- Phosphorus
45
What are Electron Shells?
1. Electrons are located in electron shells that surround the nucleus
2. Many of the electron shells in an atom are empty
3. Electron shells hold different numbers of electrons
- 1st electron shell – 2 electrons
- 2nd electron shell – 8 electrons
- 3rd electron shell – 18 electrons
46
What is the Electron Configuration?
Electron configuration is the number of electrons in each shell of an atom.
47
How can an Atom be neutral?
In an Atom the number of protons = number of electrons so an atom is neutral.
48
What are Cations?
When electrons are removed from an atom it becomes a positively charged ion or cation. This tends to happen if the outermost shell is almost empty and only filled shells will remain. Most cations are from metal atoms.
49
What are Anions?
When electrons are added to an atom it becomes a negatively charged ion or anion. This tends to happen if the outermost shell is almost full and will produce a newly filled outer electron shell. All anions come from non-metallic atoms.
50
What are Representing Ions?
Represent cations and anions with the atomic symbol for that element and the charge of the ion (in superscript).
51
What are some Examples of Representing Ions?
Some Examples are:
- Potassium ion
- Magnesium ion
- Iodide ion
- Oxide ion
52
How to name Cations?
The name is the same as the name of the element?
Expection: When there is more than one type of cations we distinguish between the two by using roman numerals for the numerals for the number of electrons lost
Examples: Copper (Cu) can lose 1 or 2 electrons (CU<+> or CU<2+> so can be copper (I) ion or Copper (II) ion
53
How can you name an Anion?
The name is similar to the name of the element but ends in –ide.
Example: Oxygen gains 2 electrons (O2-) and is named oxide, fluorine gains 1 electron (F-) and is named fluoride
54
What is Ionic Compound?
When anions and cations come together they form compounds of large crystal lattices called ionic compounds.
55
What is Ionic Bonding?
The attraction between cations and anions is called an ionic bond.
56
Why are Ionic Bonding Strong:
This type of bond is strong, ionic compounds are:
- Hard
- Brittle
- Have high melting points
57
What is Ions in solution?
Most ionic compounds are soluble in water. How easily a substance dissolves is called its solubility. When an ionic compound dissolves in water, water particles surround the cations and anions and break the crystal lattice apart, called dissociation. The ions then spread evenly in the water and are said to be in solution. If water is then removed the ions stick together in a process called recrytallisation.
58
How to describe a chemical reaction?
Signs of a chemical reaction:
- Production of heat, light, and/or sound
- Production of a gas (i.e. bubbles)
- Formation of a precipitate
- Color change
- Difficult to reverse
59
What are the Reactants?
The substances that exist before a chemical change or reaction takes place.
60
What are products?
The new substances that are formed during the chemical change.
61
What is the Chemical Equation?
Chemical equation indicates the reactants and products of a reaction.
62
How to determine the Reactants and Products in these Reactions?
1. magnesium + oxygen -> magnesium oxide
2. iron oxide + carbon -> iron + carbon dioxide
3. potassium + water ->potassium oxide + hydrogen
63
What is Law of Converation of Mass?
The law of conservation of mass states that:
- Matter (or atoms) cannot be created or destroyed during chemical reactions
- The number of atoms of each type in the reactants is equal to the number of atoms of each type in the products
- The total mass of the reactants is equal to the total mass of the products
- We represent this law in our chemical equations by having balanced equations
- Equations are balanced by placing whole numbers in front of chemical formula in a chemical equation
64
Steps for Balancng Equations?
1. Write the word equation
2. Write the correct chemical formula for all the substances in the reaction so that you get a formula equation (do not change the formulas from this point forward)
3. Use whole numbers (called coefficients) in front of the formula to balance the numbers of each element on each side of the equation
a) Start by counting the number of each element in the reactants and products
b) Adding numbers in front multiplies everything in the formula by that number
4. Check each type of atom to make sure the equation is balanced (we do not write 1's, write in the lowest common ratio)
5. Include the symbols for the states of matter
65
Balancing Chemical Equations!
```
An important point to remember!
2 NO(g) + O2(g) -> 2 NO2(g)
```
The 2 to the left of NO(g) and NO2(g) refers to the number of molecules present in the balanced equation
It is a “multiplier” for every atom in the molecule
The subscript 2 in O2 (g) and NO2 (g) refers to the number of atoms of this type that are present in each molecule (or ionic compound).
Do not change the formulas when balancing equations, only add coefficients/multipliers.
66
What are Endothermic Reactions?
Endothermic reactions are chemical reactions that absorb energy from the surroundings. Products have more energy than reactants. Reaction feels like it gets colder
67
What are some examples of Endothermic Reactions?
Example: Photosynthesis
| Plants use sunlight energy to convert carbon dioxide and water into glucose (sugar) and oxygen.
68
What are Exothermic Reactions?
Exothermic reactions are chemical reactions that release energy as heat or light. The reactants have more energy than the products. The reaction feels like it gets warmer.
69
What are some examples of Exothermic Reactions?
Examples:
Aerobic respiration: Carbohydrates (from food) is combined with oxygen releasing energy and carbon dioxide
Combustion reactions: occur when something reacts with oxygen gas (O2) to produce carbon dioxide and water
Some reactions explode or burn
Petrol: Octane (hydrocarbon) reacts with oxygen to form carbon dioxide and water vapor
Gas top: burning of methane or ethane in oxygen
70
What are Combustion Reactions?
Complete combustion reactions:
- Plenty of oxygen available
Incomplete combustion reactions:
- When oxygen is limited, other reactions occur
- Do not release as much energy as complete combustion
71
What is an Acids?
Substance that releases hydrogen ions (H+) into an aqueous solution.
72
What is a Base?
A substance that releases hydroxide ions (OH-). Bases soluble in water are also known as alkali.
73
What is an some examples of Acids?
Some Examples are:
- Hydrochloric acid (in your stomach), HCl
- Acetic acid (vinegar), CH3COOH
- Sulfuric acid, H2SO4
- Lemon juice & other citrus
- Vitamin C
74
What is an some examples of Bases?
Some examples:
- Ammonia (cleaner)
- Sodium hydroxide, NaOH
- Calcium hydroxide, Ca(OH)2
- Baking soda
- Antacids
75
What are some properties of Acids?
Some Properties:
- Corrosive
- Sour taste
- Turn blue litmus paper red
- Conduct electricity
- Neutralised by bases
76
What are some properties of Bases?
Some Properties are:
- Caustic
- Bitter taste
- Turn red litmus paper blue
- Conduct electricity
- Neutralised by acids
- Soapy, slimy feel
77
What is pH?
The concentration of hydrogen ions (H+) in a solution is measured using the pH scale
Acids pH 1-7 (more hydrogen ions present)
Bases pH 7-14 (more hydroxide ions, OH-, present)
Neutral pH 7 (neither acidic or alkaline) (e.g. pure water)
78
What are Indicators?
Indicators are chemicals that change colour to show whether a substance is acidic, neutral or basic/alkaline
Examples:
Litmus paper
Other: pH meter
79
Some Acid reaction Types?
1. Acids and metals
2. Acid and base or neutralisation
3. Acids and carbonates
80
Acids and Metals
General reaction:
acid + metal -> salt + hydrogen (gas)
Salts are ionic compounds and many are formed from an acid reacting with a metal or base
Example:
Sulfuric acid + iron ->iron (II) sulfate + hydrogen gas
H2SO4 + Fe -> FeSO4 + H2
81
Acid and Base / Neutralisation
General reaction:
acid + base -> salt + water
Acids and bases neutralise each other when mixed
Example:
Nitric acid + potassium hydroxide -> potassium nitrate + water
HNO3+ KOH -> KNO3 + H2O
82
Acids and Carbonates
General reaction:
acid + carbonate ->salt + water + carbon dioxide
Example:
Acetic acid + sodium hydrogen carbonate -> sodium acetate + water + carbon dioxide
CH3COOH + NaHCO3 -> NaCH3COO + H2O + CO2
83
What is Corrosion Reaction?
Corrosion is the breakdown of metals to form compounds
Usually occurs when exposed to water, air or other chemicals
Type of oxidation reaction
84
What are some corrosion metals?
Copper:
Verdigris – copper reacts with gases in air
Silver:
Tarnish – silver reacts with hydrogen sulfide in air
85
Explosive Corrosion Reactions
Alkali metals
- Alkali metal + water -> metal hydroxide + hydrogen
Examples: Sodium and Potassium
React explosively with just about everything!
Produce hydrogen gas!
86
What is Rust?
Iron/ Steel
Reacts with water and oxygen in the air
Forms flaky rust [iron (III) oxide] making metal thinner & weaker
87
What is Corrosion of Aluminium?
Aluminium immediately reacts with air forming a fine layer of grey aluminium oxide.
This layer does not flake, it is tightly bound and protects the Al from further corrosion
Anodising: Deliberate build up of aluminium oxide to protect underneath
