Atoms elements compounds Flashcards
What’s the relative mass of Protons neutrons and electrons?
Proton: 1
Neutron: 1
Electron: 0 (1/1836)
what are the relative charges of protons neutrons and electrons
Protons: +1
Neutrons: 0
Electrons: -1
Why do Atoms contain equal numbers of protons and electrons?
Atoms are stable with no Overall charge
Protons have a relative charge of -1 so there must be an equal number for the charges to balance.
what does atomic number represent?
The number of Protons in an atomic nucleus.
what does the mass number of an atom mean
the total number of protons and neutrons found in the nucleus of an atom
how are elements arranged in the periodic table?
in order of increasing atomic number. Elements with similar properties are in the same group
why do elements in the same group have similar properties?
Elements in the same group have the same number of electrons in the outer shell which determines how they react.
what does the periodic (row) number tell you about elements in that period?
They all have the same number of electron Shells e.g all elements in period 4 have 4 shells of electrons
what are isotopes?
Atoms of an elements with the same number of protons but a different number of nuetrons.
Isotopes of an element have the same atomic number but different atomic mass
why do isotopes have the same properties? (extended only)
because they have the same number of electron in their outer shell so they react in the same way.
what are the two types of isotope?
radioactive and non-reactive
medical use of isotopes
Tracers
Cancer treatment
Lung and organ imaging
Anemia diagnosis
Industrial use of isotopes
smoke alarms
Tracer (to find leaks in pipes for example)
sterilisation
how are electrons arraigned in an atom?
in shells around the nucleus
the maximum number of electrons in the first 3 shells is 2,8,8 the first shell can hold 2 electrons and the second and third can hold 8
what is the most stable electron configuration?
the full outer shell of electrons
for the first shells this is either (2), (2,8) or (2,8,8)
Atoms react in order to gain a full outer shell so that they become more stable
which group are the noble gasses in the periodic table?
Group 8
Known sometimes as Group Zero
why are the noble gasses very unreactive?
the noble gassed all have a full outer shell meaning they already have the most stable electron configuration. As a result, they do not react easily.
what is the difference between an element and a compound?
An element is a substance made up of only one type of atom whereas a compound is made up of two or more chemically combined elements
what is a mixture?
contains 2 or more elements/compounds which are not chemically combined.
what is a metal and where are they found in the periodic table?
Metals are found towards the left and bottom of the table.
Metals lose electrons to form positive ions.
what is a non metal and where are they found in the periodic table
non metals are found towards the top right of the periodic table
non metals gain electrons to form negative ions
what is an alloy?
A mixture containing a metal and another element ( could be a different metal or a non metal)
why are alloys harder than pure metals?
Atoms in pure metals are arranged in uniform rows which can easily slide over each other, making them very malleable.
Alloys contain different sized atoms which distort these lavers meaning the layers are unable to slide, increasing the hardness of the material.
what is a brass? what is it used for?
Brass is an alloy of copper and zinc
Brass is hard and resistant to corrosion so it can be used for decorative hardware like plumping fittings
what are ions?
positively/negatively charged atoms
how are ions formed?
Positive ions form when an atom loses electrons
Negative ions form when an atom gains electrons.
what are cations and anions?
Cation - Positive Ion
Anion - Negative Ion
How are Ionic bonds formed between group 1 and 7 elements
Group I elements lose their only outer shell electron to form 1+ ions. Group VIl elements have seven electrons in their outer shell and can gain the electron lost from the group 1 element to form ions with a 1- charge.
An ionic bond can form between these oppositely charged ions.
What types of elements add ionic bonds formed between? Ext
lonic bonds form between metals and non-metals.
Metal lose electrons to form positive ions.
Non-metals gain electrons to become negative ions.
Describe Structure of an ionic compound
- Giant lattice structure.
- Regular alternating arrangement of positive and negative ions.
- Held together by electrostatic attraction between oppositely charged ions.
What’s a covalent bond?
A bond formed when two non metals share a pair of electrons
why do atoms form covalent bonds
to obtain more stable electron configuration
Give an example of a compound that contains atleast 1 covalent bond
Hydrogen Chlorine Water Methane Ammonie Hydrochloric acid
Explain formation of the covalent bonds in carbon dioxide CO2
Carbon has the electron configuration (2, 4) and oxygen has the electron configuration (2, 6).
The carbon atom forms a double covalent bond with each oxygen atom. This means each oxygen shares two pairs of electrons with the carbon. In total, the carbon will gain 4 electrons as it shares by a total of four electron pairs.
Explain the formation of covalent bonds in nitrogen
A nitrogen atom has the electron configuration (2, 5).
A triple covalent bond forms between the nitrogen atoms with three pairs of electrons shared between them.
