Atomic structure and periodic table

• The atomic number is the number of protons

  
• Atoms are made up of protons, neutrons and electrons.
• Protons are positively charged, electrons are negatively charged.
• The number of neutrons in an atoms nucleus is called the mass number.
• In the periodic table, the group number represents the number of electrons in the outer shell.
• At the top of the periodic table, outer electrons are close to the nucleus and said to have strong attraction whilst those towards the bottom have outer electrons which are far from the nucleus and therefore have weaker attraction.
• Elements in the same group have similar properties.
• Isotopes are atoms of the same element with the same number of protons but different number of neutrons
• Isotopes have the same atomic number but a different mass number.
• Relative atomic mass is the average mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12
• Group 0 elements are unreactive as they have full outer shells.
• Atomic mass is equal to the sum of the protons and neutrons.
• All atoms of the same element have the same number of protons.
• Non-metals are brittle and do not conduct electricity. They have low melting and boiling points are are not magnetic.
• Non-metals do not react to form positive ions.
• Metals react to form positive ions. They lose electrons to form positive ions.
• Metals are good conductors of heat and electricity because they have free electrons that can move around the metal lattice.
• Metals have high melting and boiling points.
• Group 0 elements are called noble gases. They are inert and non-reactive.
• Group 1 elements are called alkali metals because they react with water to form alkaline solutions.
• When an alkali metal reacts with water, it forms a metal hydroxide and hydrogen.
• When an alkali metal reacts with oxygen, it forms a metal oxide.
• Group 7 elements are called halogens. They are very reactive and form ions with a positive charge.
• When halogens react with non-metals they share electrons by covalent bonding to achieve full outer shells.
• More reactive halogens are found in the earths atmosphere as they are more reactive than the less reactive halogens
• Atoms are the smallest part of an element that can exist.
• Air is a mixture, it is made up of more than one element which are not chemically combined.
• Chemical properties of an element are not impacted by being part of a mixture.