Atoms, Elements & Compounds Flashcards
State what is meant by the term element.
An element is a substance made of atoms that all contain the same number of protons and cannot be split into anything simpler.
State what is meant by the term compound.
A compound is a pure substance made up of two or more different elements chemically combined together.
What is a mixture?
A mixture is a combination of two or more substances (elements and/or compounds) that are not chemically combined.
What is the difference between a compound and a mixture?
A compound consists of two or more elements that are chemically combined, while a mixture consists of two or more substances that are not chemically combined.
What is the difference between an element and a compound?
An element consists of only one element, while a compound consists of two or more elements that are chemically combined.
What is the mass and charge of a proton?
A proton has a relative mass of 1 and a charge of +1.
What is the mass and charge of an electron?
An electron has a negligible mass and a charge of -1.
Which subatomic particles are in the nucleus of an atom?
The subatomic particles in the nucleus of an atom are protons and neutrons.
How do you calculate the number of neutrons in an atom?
mass number - atomic number
Which subatomic particle has a mass of 1 and a charge of 0?
The subatomic particle with a mass of 1 and a charge of 0 is the neutron.
How do you determine the number of electrons in an atom?
The number of electrons in an atom is the same as the number of protons / the atomic number.
Why are atoms are electronically neutral?
Atoms are electrioncally neutral because they have the same number of electrons as protons.
Which sub-atomic particle is not found inside the nucleus?
The sub-atomic particle that is not found inside the nucleus is the electron.
Calculate the number of protons, neutrons and electrons in an atom of ²⁷₁₃Al
Protons = 13
Neutrons = 27 - 13 = 14
Electrons = 13
What is another term for mass number of an atom?
Another term for mass number is nucleon number.
What does atomic number tell us about an atom?
Atomic number tells us the number of protons in the nucleus of an atom.
What is an electronic configuration?
An electronic configuration is the arrangement of electrons in shells.
What is the maximum number of electrons in the first shell?
The first shell can hold a maximum of 2 electrons.
What information does the group give about the electronic configuration?
The group gives the number of outer electrons.
State the electronic configuration of sulfur.
The electronic configuration of sulfur is 2, 8, 6.
What does the last number in an electronic configuration represent?
The last number in an electronic configuration represents the number of outer electrons.
What is the maximum number of electrons in the second and third shells?
The second and third shells can each hold a maximum of 8 electrons.
In terms of electrons, what are other words for shell?
Orbit
What is the electronic configuration of carbon?
The electronic configuration of carbon is 2.4.
Which element has the electronic configuration 2.8.1?
The element with the electronic configuration 2.8.1 is sodium.
Silicon has ….. electron shells and ….. outer electrons .
Silicon has 3 electron shells and 4 outer electrons .
State two pieces of information required to calculate the relative atomic mass of an element.
The mass numbers of each isotope.
The (relative / percentage) abundances of each isotope.
State the equation for Ar in terms of the percentage abundance and mass of isotopes A and B.
% of isotope A + % of isotope B / 100
In terms of isotopes, what is abundance?
In terms of isotopes, abundance is the amount of each isotope present in a sample of an element.
How can you recognise isotopes from their chemical symbol?
Isotopes have the same symbol and same atomic numbers but different mass numbers.
What is an isotope?
An isotope is an atom of the same element containing the same number of protons but different numbers of neutrons.
What determines the chemical characteristics of an atom?
The chemical characteristics of an atom are determined by the number of electrons in the outer shell.
What is an ion?
An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons.
Are anions positive or negative ions?
Anions are negative ions.
How are anions formed?
Anions are formed when atoms gain electrons.
Do metals lose or gain electrons to other atoms?
Metals lose electrons to other atoms.
Why do non-metals gain electrons?
Non-metals gain electrons to obtain a full outer shell of electrons.
What type of ion do metals usually form?
Metals usually form cations / positive ions.
Give two reasons why are cations positively charged.
Cations are positively charged because:
They have lost electrons
They have more protons than electrons
How many electrons does a sulfur atom gain to become a sulfide ion, S2-?
A sulfur atom gains 2 electrons to become a sulfide ion, S2-.
How many electrons does a Group 1 element lose to become a 1+ ion?
A Group 1 element loses 1 electron to form a 1+ ion.
What does a dot and cross diagram show?
A dot and cross diagram shows the transfer of electrons between atoms to form ions in an ionic bond.
In the formation of sodium chloride, which atom loses an electron?
In the formation of sodium chloride, the sodium atom loses an electron.
What happens to a Group 7 atom when it reacts with a Group 1 atom?
When a Group 7 atom reacts with a Group 1 atom, the Group 7 atom: Gains one electron. Becomes negatively charged / becomes a 1- ion.
How are ions attracted to one another in an ionic compound?
The ions are then attracted to one another and held together by electrostatic forces
What is the composition of lattices formed by ionic compounds?
Lattices formed by ionic compounds consist of a regular arrangement of alternating positive and negative ions.
What is the structure of ionic compounds called?
The structure of ionic compounds is called a giant ionic lattice.
Are ionic compounds usually solid or liquid at room temperature?
Ionic compounds are usually solid at room temperature.
What are electrostatic forces?
Electrostatic forces are the attractive (or repulsive) forces between charged particles.
Why are ionic compounds soluble in water?
Ionic compounds are soluble in water because they are polar.
In an ionic lattice, what direction do the electrostatic forces act in?
In an ionic lattice, electrostatic forces act in all directions.
What is represented by a short straight line between two atoms?
A short straight line between two atoms represents a covalent bond.
What is a covalent bond?
A covalent bond is a type of chemical bond where atoms share pairs of electrons with each other.
What type of materials form a covalent bond?
The materials that form covalent bonds are non-metals.
What makes each atom more stable in a covalent bond?
Sharing electrons in the covalent bond allows each atom to achieve an electron configuration similar to a noble gas.
What is formed when a group of two or more atoms covalently bond together?
A compound / molecule is formed when a group of two or more atoms covalently bond together.
What is the smallest molecule?
The smallest molecule is hydrogen, H2.
What do dots and crosses represent in a dot and cross diagram?
In a dot and cross diagram, dots and crosses represents electrons.
What type of bond is formed if three pairs of electrons are shared between two atoms?
A triple bond is formed if three pairs of electrons are shared between two atoms.
What type of covalent bond exists between the two carbon atoms in ethene, C2H4?
A double bond exists between the carbon atoms in ethene.
What is the difference between covalent bonds and intermolecular forces?
Covalent bonds are strong bonds that hold atoms together within a molecule, while intermolecular forces are weak attractive forces that exist between different molecules.
What are simple molecular structures?
Simple molecular structures are small molecules with covalent bonds, which have weak forces between the molecules (intermolecular forces).
Why are covalent compounds generally poor conductors of electricity?
Covalent compounds are generally poor conductors of electricity because they do not contain free ions or electrons to carry the current.
What happens to melting and boiling points as the relative molecular mass of a substance increases?
As the relative molecular mass of a substance increases, the melting and boiling points also increase due to the increased number of electrons and stronger intermolecular forces.
What are insulators?
Insulators are materials that do not allow the flow of electric charge or heat, and common insulators include plastics, rubber, and wood.
Why do simple molecular structures have low melting and boiling points?
Simple molecular structures have low melting and boiling points due to weak intermolecular forces which require small amounts of energy to overcome.
What are giant covalent structures?
Giant covalent structures are macromolecules or giant lattices that consist of a huge number of non-metal atoms with strong covalent bonds in a fixed ratio.
Define allotropes.
Allotropes are different structural forms of the same element, such as diamond and graphite for carbon.
Why does diamond not conduct electricity?
Diamond does not conduct electricity because all of the outer shell electrons are held in the covalent bonds, and there are no freely moving delocalised electrons to carry the current.
Describe the structure of graphite
In graphite:
Each carbon atom is bonded to three others.
There are hexagonal layers.
There is one free / delocalised electron per carbon atom.
State the properties of diamond.
Diamond does not conduct electricity, has a high melting point, and is extremely hard.
What are the properties of graphite?
Graphite conducts electricity and heat, has a high melting point, and is soft and slippery.
Explain why graphite conducts electricity.
Graphite conducts electricity because it has delocalised electrons that can move / flow (throughout the structure)
Why is diamond hard?
Diamond is hard because its rigid, tetrahedral structure contains a lot of covalent bonds that require a large amount of energy to break.
Why is graphite soft?
Graphite is soft because there are weak intermolecular forces betwen the layers, which allows the layers to slide over each other.
What is silicon(IV) oxide?
Silicon(IV) oxide is a macromolecular compound that occurs naturally as sand and quartz, with the chemical formula SiO2.
How many oxygen atoms does each silicon atom bond with in silicon(IV) oxide?
In silicon(IV) oxide, each silicon atom forms covalent bonds with 4 oxygen atoms.
Define a macromolecular compound.
A macromolecular compound is a substance composed of very large molecules with a repeating structure.
How does silicon(IV) oxide compare to diamond in terms of properties?
Silicon(IV) oxide has similar properties to diamond, including being very hard, having a very high boiling point, being insoluble in water, and not conducting electricity.
What are two common uses of silicon(IV) oxide?
Two common uses of silicon(IV) oxide are making sandpaper and lining the inside of furnaces.
What type of bonding is present in silicon(IV) oxide?
Silicon(IV) oxide has covalent bonding.
How many silicon atoms does each oxygen atom bond with in silicon(IV) oxide?
In silicon(IV) oxide, each oxygen atom forms covalent bonds with 2 silicon atoms.
What is another name for silicon(IV) oxide?
Another name for silicon(IV) oxide is silicon dioxide or silica.
What is metallic bonding?
Metallic bonding is the strong electrostatic force of attraction between delocalised electrons and positively charged metal ions.
What are delocalised electrons in metals?
Delocalised electrons are electrons in metals that do not belong to any particular metal atom and are free to move throughout the metal lattice.
Why can metals conduct electricity?
Metals can conduct electricity because they have free electrons available to move and carry charge.
What allows metals to be malleable and ductile?
Metals are malleable and ductile because the layers of positive ions can slide over one another.
Why do metals have high melting and boiling points?
Metals have high melting and boiling points because they contain many strong metallic bonds, which require a lot of heat energy to overcome.
Describe the structure of a metal
Metal structures are positive metal ions arranged in a regular pattern, with a “sea” of delocalised electrons moving freely between them.
