Atoms, Periodic Table and Electrons Flashcards
What is a molecule?
A molecule is when two or more atoms join together in a chemical bond. When atoms joined together that are all the same, they are called an element, however when different atoms are joined together, that is a compound.
What is an atom?
All matter consists of particles called atoms. An atom is a basic chemical building block of matter and is the smallest part of an element still recognised as that element.
What is an atom made up of?
Atoms are made up of three subatomic particles: protons, neutrons and electrons.
What charge does an atom have?
A ‘zero’ electrical charge. From the subatomic particles, protons have a positive charge, neutrons have a neutral charge and electrons have a negative charge. The charges of protons and electrons are equal in magnitude, yet opposite in direction and protons and electrons are electrically attracted to each other.
What charge do protons have?
A particle with a positive electrical charge - electrically attracted to electrons and equal in magnitude to a electron, but opposite in sign. Found in the nucleus of an atom.
What charge do electrons have?
A tiny particle with a negative electrical charge - electrically attracted to protons, equal in magnitude to protons, but opposite in sign. Electrons orbit the nucleus of atoms or ions in shells.
What charge does a neutron have?
Each neutron is electrically neutral, carrying no charge and is found in the nucleus of an atom.
What is the mass of protons, electrons and neutrons?
Protons and neutrons are essentially the same size, with the mass of a proton equal to the mass of a neutron. Both are much larger than an electron - with the mass of a proton 1843 times larger than that of an electron.
Where is the mass and volume of an atom?
All the mass of an atom is in its nucleus - the volume is in its outer shell
What charge does the nucleus have?
The nucleus has a positive charge as it contains protons and neutrons.
Protons
A proton is a sub-atomic particle which the atom is part of. It has a positive electrical charge and is equal in magnitude with an electron, but has an opposite sign. It is electrically attracted to an electron. Protons are the same size as neutrons, with roughly the same mass as neutrons, but the mass of a proton is about 1843 times larger than that of an electron. The nucleus of an atom contains protons and neutrons, so has a positive electrical charge and almost all the mass of an atom is contained in its nucleus. The number of protons(atomic number) determines the element. All atoms of a given element have the same number of protons and atoms of different elements have different numbers of protons. Isotopes and ions of an atom with a constant number of protons are all variations of the same element. Isotopes have the same atomic number and different mass numbers to protons. It’s harder to add or remove a proton or neutron from an atom than an electron. A proton has a relative charge of +1 and relative mass of 1. Protons wouldn’t be able to stick together if it wasn’t for the neutrons that hold the protons together in the nucleus through strong forces. An atom has the same number of protons and electrons which have equal and opposite charges, meaning an atom has no overall charge. The mass number of an atom is the total number of protons and neutrons found in the nucleus(they are usually whole numbers).Atoms of different elements usually have different mass numbers, but they can be the same. The symbol of an atom can be shown to have the mass number at the top and atomic number at the bottom.
For an element(atom):
number of protons = atomic number
number of electrons = atomic number
number of neutrons = mass number - atomic number
Mass number = Proton Number + Neutron Number
Model for Ion:Charged Atom
1)
64. 2+
Cu
29
Atomic Number = Proton Number
Mass number = Proton number + neutron number=
Particles in the nucleus
Neutron number = Mass number - Atomic Number
Electron number = Proton Number - 2
Protons = 29 Neutrons = 64 - 29= 35 Electrons = 29-2=27
2). 16. 2-
O
8
Atomic Number = Proton Number
Mass Number = Proton Number + Neutron Number=
Particles in the nucleus
Neutron number = Mass number - Atomic Number
Electron number = Proton Number +2
Protons = 8
Neutrons=16-8=8
Electrons=8+2=10
The relative atomic mass number is a weighted average of the masses of the atoms of the isotopes. It takes account of how much of the isotopes there is in each element. Relative atomic mass numbers are rounded to the nearest whole number, but aren’t actually whole numbers. You must know the mass numbers of these isotopes and the abundance of these isotopes.
Chlorine exists as two isotopes:
Cl35) 35
Cl
17
Cl37) 37
Cl
17
Abundance of Cl35=75%
Abundance of Cl-37=25%
Relative atomic mass number = (75x35)+(25x37)/(75+25)= 2625+925/100= 3550/100= 35.5
Models of the atom are used to identify its structure.
The solid sphere model pictures the atom as a tiny, hard, unchanged sphere.
The plum pudding model pictures the atom
as a soft, positively charged sphere with small light ‘currants’ of negative charge spread through it.
The large nucleus model pictures the atom with a heavily positively charged part called the nucleus which takes most of the centre of the atom, with light negative electrons occupying the rest.
The small nucleus model pictures the atom with a tiny, heavy positively charged nucleus in the centre, with the rest of the space occupied by light negative electrons.
When a proton is fired at a positively charged sphere, the proton moves away from the sphere as like charges repel each other.
Electrons
An electron is one of the sub-atomic particles of which an atom is made up of.
Each electron has a negative electrical charge which is equal in magnitude to the positive charge of a proton but opposite in sign. Electrons are electrically attracted to protons.
The mass of a proton/neutron is 1843 times larger than that of an electron. Electrons are the smallest of the three particles.
Electrons orbit the nucleus in shells that surround the central nucleus.
Almost all of the volume of an atom is contained in electrons, but the mass of an atom is concentrated on its nucleus.
Varying the number of electrons results in ions.
Ions of an atom with a constant number of protons are variations of the same element.
Electrons are easier to add or remove from an atom than a proton or neutron bound together by powerful forces.
Chemical reactions largely involve atoms or groups of atoms and interactions between their electrons.
Relative charge = -1
Relative mass=
1/2000
Electrons are in constant motion in the space around the nucleus and give the atom a ‘fuzzy’ edge.
Electrons have a -1 charge and can move from one atom to another or be shared by separate atoms.
If an atom is neutral, it will have the same number of electrons as protons.
An electronic structure is the way electrons are arranged in an atom.
Electrons in atoms occupy energy levels(electron shells) outside the nucleus. Different shells can hold different maximum numbers of electrons.
The electrons in an atom occupy the lowest available energy level first. This is the shell nearest to the nucleus and when this shell is full the electrons begin to occupy the next energy level.
Maximum number of electrons an element(with atomic numbers 1-20) can have for each of its energy shells:
First Shell = 2 electrons
Second Shell=8 electrons
Third Shell=8 shells
Predicting an electronic structure:
Electron configuration tells the arrangement of electrons in the shells of the atoms of the elements.
The electronic structure of an atom can be predicted from its atomic number. The atomic number of sodium is 11, meaning sodium has 11 protons and 11 electrons. This electronic structure is written as:
2,8,1.
This can be represented in a diagram. A circle represents a shell and each electron is shown as a dot or cross.
The electronic structure of an element is linked to its position on the periodic table.
Number of shells = Period Number
Number of electrons in outermost shell =
Group number
Numbers added together = Atomic Number
When an atom gains or loses electrons, they develop a charge as electrons are negatively charged. These charged particles are called ions. When an atom loses electrons they become positively charged. Positively charged ions are called cations. When an atom gains electron, they become negatively charged ions called anions.
Model 1)
Na Electronic Structure: 2,8,1
Sodium has one electron in its outermost shell. When it loses this electron, sodium becomes positively charged sodium ion.
Na+ Ion
Model 2)
Oxygen Electronic Structure:2,6
There are 6 electrons on the outermost shell of oxygen. Oxygen gains two electrons to form a negatively charged O2-(Oxide Ion).
Both ions have a complete outer shell and the same structure as a noble gas(neon ion).
Model 3)
Sodium and Magnesium are both metals which lose their valence electrons to form cations.
Model 4)
Group 1 Metals like Na have one valence electron which they lose to form a +1 Charge,
Model 5)
Group 2 Metals like Mg have two valence electrons which they lose to form a +2 charge.
Non-metals tend to gain electrons to form anions.
Model 1) Oxygen is in Group 6 and has six valence electrons. It gains two electrons to form an ion with a -2 charge.
Model 2) Fluorine is in Group 7 and has seven valence electrons. It gains one electron to form an ion with a -1 charge.
Group 3 Elements lose three ions to forn ions with a +3 charge.
Group 5 Elements gain three electrons to form ions with a -3 charge.
Group 4 Elements like carbon form covalent compounds.
Neutrons
A neutron is a sub-atomic particle which an atom is made up of,. It is electrically neutral, doesn’t have a charge and isn’t attracted to electrons or protons.
Protons and neutrons are the same size as each other and are 1843 times greater than the mass of an electron.
The nucleus of an atom contains protons and neutrons and has a positive electrical charge. Since the nucleus contains protons and electrons, most of an atom’s mass is concentrated on its nucleus.
Almost all of the mass of an atom is in its nucleus.
Varying the number of neutrons results in isotopes.
Isotopes with a constant number of protons are all variations of the same element.
Protons and neutrons are bound to electrons by powerful forces, meaning it’s harder to remove protons or neutrons from an atom than an electron.
Neutron Relative Charge = 0
Neutron Relative Mass=
1
For Elements and Ions:
Atomic Number = Proton Number
Mass Number = Proton Number + Neutron Number = Particles in the Nucleus
Neutron number = Mass number - atomic number
There are models that represent the structure of an atom:
- The solid sphere model pictures the atom as a tiny, very hard, unchanged sphere which deflects all particles.
- The plum pudding model pictures the atom as a soft, positively charged sphere with negative charge spread through it.
There’s no heavy charged nucleus to deflect the particles, they pass through with small deflection. - The large nucleus model pictures the atom with a heavy positively charged nucleus and light, negative electrons. It deflects most of the particles, but some particles pass through the outer part of the atom.
- The small nucleus model pictures the atom with a tiny, heavy positively charged nucleus and light, negative electrons. This strongly repels the particles that come near it. Most particles don’t go near the nucleus and pass through the atom without deflection.
What is an element?
An element is a pure substance made up of only one kind of atom having the same atomic number. An Element cannot be broken down into anything simpler by chemical means. Some elements consist of single atoms, others consist of molecules.
Diatomic Molecules
Two atoms of the same non-metal element chemically bonded together. These 7 Elements exist as diatomic(two-atom) molecules:
H2, N2,O2, F2,
Cl2, Br2, I2
