c1 atomic structure

• Elements consist of only one type of atom
• Compounds are formed from elements by chemical reactions
• Mixtures consist of two or more elements or compounds not chemically combined together
• Mixtures can be separated by physical processes such as filtration, crystallisation, simple distillation, fractional distillation, and chromatography
• Atoms have no overall electrical charge
• Atoms are very small, having a radius of about 0.1 nm
• The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element
• The electrons in an atom occupy the lowest available energy levels
• The elements in the periodic table are arranged in order of atomic number
• Elements in the same group in the periodic table have the same number of electrons in their outer shell
• The elements in Group 0 of the periodic table are called the noble gases
• The elements in Group 7 of the periodic table are known as the halogens
• The transition elements are metals with similar properties which are different from those of the elements in Group 1
• Many transition elements have ions with different charges, form colored compounds and are useful as catalysts
• All substances are made of atoms
• An atom is the smallest part of an element that can exist
• Atoms of each element are represented by a chemical symbol
• There are about 100 different elements shown in the periodic table
• Compounds are formed from elements by chemical reactions
• Compounds contain two or more elements chemically combined in fixed proportions
• Compounds can only be separated into elements by chemical reactions
• Mixtures consist of two or more elements or compounds not chemically combined together
• New experimental evidence may lead to a scientific model being changed or replaced
• Almost all of the mass of an atom is in the nucleus
• The relative atomic mass of an element is an average value that takes account of the abundance of the isotopes of the element
• Elements in the same group in the periodic table have the same number of electrons in their outer shell
• Metals react to form positive ions and lose outer shell electrons
• The boiling points of the noble gases increase with increasing relative atomic mass
• The transition elements are metals with similar properties different from those of the elements in Group 1