Additional Science: Chemistry (II) Flashcards
Draw and label an atom
What are the masses and charges of these parts of an atom
Proton
Neutron
Electron
Protons = +ve (mass 1)
Neutrons = neutral (mass 1)
Electrons = -ve (mass 1/2000th)
Why do atoms usually have no overall electrical charge?
Atoms usually have no overall charge because they have equal numbers of protons (+ve) and electrons (-ve), which cancel one another out
All atoms of a particular element (e.g. carbon) all have the same number of what?
Protons
What are the following numbers called?
a = relative atomic mass
b = atomic number
What do the numbers tell you about the atom?
a = relative atomic mass – the number of protons and neutrons in the atom
b = atomic number – the number of protons (usually the same as the number of electrons)
What is an alloy and why are they used?
Give some examples
Alloys are mixtures of metals with other elements, e.g. iron + carbon → steel
They have a combination of properties, e.g. bronze, brass, steel etc…
What is a smart alloy and why are they used (shape-memory)?
Give some examples
Smart alloys can return to their original shape after being deformed – e.g. glasses and braces
What do these terms means: -
Element
Compound
Mixture
Element – pure substance with only 1 type of atom (e.g. gold)
Compound – 2 or more elements chemically bound (e.g. carbon dioxide)
Mixture – more than 1 element or compound not chemically bound (e.g. air)
What are the symbols for the following atoms: -
Oxygen
Nitrogen
Chlorine
Hydrogen
Sodium
Copper
Potassium
Helium
Calcium
Zinc
Iron
Carbon
Oxygen (O)
Nitrogen (N)
Chlorine (Cl)
Hydrogen (H)
Sodium (Na)
Copper (Cu)
Potassium (K)
Helium (He)
Calcium (Ca)
Zinc (Zn)
Iron (Fe)
Carbon (C)
What happens to atoms when they chemically react to form a compound?
They share, give away, or take electrons
What are the names of these compounds, and which atoms are found in them?
H2O
CaCO3
H2SO4
HCl
CO2
Water (H2O)
Calcium carbonate (CaCO3)
Sulfuric acid (H2SO4)
Hydrochloric acid (HCl)
Carbon dioxide (CO2)
What is an isotope?
An isotope is an atom with a different amount of neutrons
Use the periodic table to draw the electron structure of the following: -
Neon
Calcium
Sodium
How can you tell which group these atoms are in?
The number of electrons in the outer shell is the same as their group number
How many electrons can occupy the 1st and 2nd shell (energy level) of an atom?
2 in the 1st shell and 8 in the 2nd shell
The electron structure of sodium can be represented as 2,8,1 – what does this mean?
Represent these atoms: -
Fluorine
Oxygen
Potassium
Magnesium
2,8,1 means 2 electrons in the 1st shell, 8 electrons in the 2nd shell and 1 electron in the 3rd shell
Fluorine = 2,7
Oxygen = 2,6
Potassium = 2,8,8,1
Magnesium = 2,8,2
Define these terms: -
Element
Compound
Mixture
Element – a pure substance made from 1 type of atom only
Compound – 2 or more elements chemically bound
Mixture – 2 or more elements or compounds mixed together which are not chemically bound
What happens to the electrons of 2 atoms when they chemically react?
During a chemical reaction electrons are either given away, taken, or shared
What is an ion?
How are +ve ions formed?
How are -ve ions formed?
An ion is an atom with a charge
+ve ions have lost electrons
-ve ions have gained electrons
Explain how the following atoms become ions (will they be +ve or –ve)?
Potassium
Magnesium
Chlorine
Oxygen
Potassium – loses 1 electron (K+)
Magnesium – loses 2 electrons (Mg2+)
Chlorine – gains 1 electron (Cl-)
Oxygen – gains 2 electrons (O2-)
Use diagrams to show how these atoms for ionic bonds: -
Sodium + Chlorine
Describe and use a diagram to show the structure of ionic compounds
Ionic compounds have a giant structure – they are bonded to 6 other ions by electrostatic bonds
What are the melting and boiling points of ionic compounds like?
Why is this?
Ionic compounds have high melting points and boiling points – to melt them you have to supply enough energy to break the 6 bonds attached to each ion
What happens to the electrons when atoms form ionic bonds and covalent bonds?
Which is the strongest?
Ionic bonds – 1 atom loses electrons and another gains electrons
Covalent bonds – electrons are shared
An individual covalent bond is stronger than an ionic bond
Use diagrams to show how the following compounds are formed: -
Hydrogen
Oxygen
Hydrogen Chloride
Use a diagram to show how water is formed
Water (H2O)
What are the melting and boiling points of covalent compounds like?
Explain why this is
Covalent compounds have low melting and boiling points (are often gases) as there is no attraction between the molecules
How are the elements of the periodic table arranged?
What are the rows called?
What are the columns called?
Elements are arranged in order of atomic number
Rows are called periods
Columns are called groups
Which 2 elements would be out of order in the periodic table if they were arranged by atomic mass instead of atomic number?
Potassium and Argon
Why do elements in the same group have similar properties?
Elements in the same group have similar properties as they all have the same number of electrons in their outer shell
What do these symbols mean?
(s)
(l)
(g)
(aq)
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous
What are the symbols for these compounds?
Calcium carbonate
Sodium chloride
Hydrochloric acid
Calcium carbonate – CaCO3
Sodium chloride – NaCl
Hydrochloric acid - HCl
Why do covalent compounds not conduct electricity when dissolved?
Covalent compounds do not conduct because they do not break down into ions
Give the names of 3 covalent compounds which have giant ionic structures?
What is the structure of each like?
Diamond – 4 carbon-carbon covalent bonds
Graphite – 3 carbon-carbon covalent bonds
Silicon dioxide – 2 double silicon-oxygen covalent bonds
Why does graphite conduct electricity?
Graphite conducts electricity because it is only bonded 3x (meaning there is a delocalised electron to pass the charge)
Explain why ionic compounds have a giant structure
Ionic compounds have giant structures because the ions keep their charge and attract up to 6 other ions – forming a giant lattice
What does monatomic mean and why are noble gases monatomic?
Monatomic means an atom which only exists on its own (does not react)
Noble gases are monatomic as they have a full shell and are un-reactive
What does diatomic mean and why are elements such as the halogens, hydrogen and oxygen diatomic?
Diatomic – atoms in pairs, e.g. H2 and O2
Halogens will form diatomic molecules because they covalently bond with each other, forming pairs
What is the bonding in metals like?
The bonding in metals creates delocalised electrons (free to move and pass on electrical current)
Why do metals conduct electricity?
The bonding in metals creates delocalised electrons (free to move and pass on electrical current)
Why do ionic compounds conduct electricity when they are dissolved / molten?
Ionic compounds conduct electricity when dissolved or molten because they remain as ions (which will pass a current)
What are the symbols for these compounds?
Sulfuric acid
Sodium hydroxide
Nitric acid
Sulfuric acid = H2SO4
Sodium hydroxide = NaOH
Nitric acid = HNO3
Use diagrams to show how magnesium oxide forms ionic bonds
Use diagrams to show how calcium chloride forms ionic bonds
Use diagrams to show how methane (CH4) is formed
Use diagrams to show how ammonia (NH3) is formed
What are the symbols for these compounds?
Magnesium oxide
Ammonia
Methane
Magnesium oxide = MgO
Ammonia = NH3
Methane = CH4
Which group of the periodic table do not form ions?
Explain why this is
Noble gases do not form ions as they already have a full outer shell
What are the names of the following groups in the periodic table?
Group 1
Group 2
Middle metals
Group 7
Group 0
Group 1 = alkali metals
Group 2 = alkaline Earth metals
Middle metals = transition metals
Group 7 = halogens
Group 0 = Nobel gases
What are nano-materials and what are they used for?
Nano-materials (1-100nm) are very small (one nano-metre = one-thousand-millionth of a metre)
They are used for self-cleaning coats on glass etc…