Chem Test Objectives Flashcards
Describe the first periodic table developed by Mendeleev
He created a periodic table of all the elements that were known at the time. He organized by similarity of the elements properties, such as estimate of atomic mass, color, density, melting point, known chemical reactivity into rows and columns. Within a row, elements with lower atomic masses were on the left. All the metals ended up on one side, and the non-metals ended up on the other, the metalloids were in the middle.
Describe the modern periodic table.
18 vertical columns (groups), 7 horizontal rows (periods). Elements in a group have similar chemical and physical properties since the have the same amount of outer electrons (with the exception of the full valence electrons in group 18, which is a similar property). The elements are arranged in order of increasing atomic number.
Explain the structure of an atom.
Atoms consist of an extremely small, positively charged middle called the nucleus, surrounded by a cloud / orbitals of negatively changed particles, called electrons.
First Nations understanding of Matter
The indigenous people understand matter using the medicine wheel, and comprises the four elements, wind rock, Fire and Water. A part of something only has meaning in terms of its relationship to the whole thing.
Modern Science of understanding matter / chemistry
Anything that has mass and takes up space. All matter has to be in one or a combination of the four states. They break apart / analyze things into their smaller parts, then study the parts separately in great detail.
Thomson development of atomic theory.
He described an atom as plum pudding. He said the atom is a positively charged sphere with electrons scattered throughout randomly.
Thomson Expermient
He was able to expel electrons from atoms in cathode ray tubes.
Rutherford’s development to atomic theory.
The atom consists of a small, positively charged, dense nucleus in the Center and electrons surround the nucleus, and occupies most of the space, but a small fractions of its mass.
Rutherford experiment
He shot positvely charged particles at a gold foil, and he discovered 0.01% of the charges bounced back while all the others went through.
Bohrs development to atomic theory.
He found out that the electrons were not randomly scattered but arranged in specific energy levels around the nucleus. Each energy level can only have a specific maximum amount of electrons.
