Elements and the Periodic Table

1. Elements and the Periodic Table Organizing the elements. Mendeleev – organized the first periodic table. First attempt was by atomic mass. Periodic Table – a table containing all of the known elements in our universe. It is known for its regular repeating pattern.

2. Inside Atoms • Nucleus – the core of an atom, containing the protons and neutrons. • Proton – small particle within a nucleus which along with the neutron contains most of the mass of the atom. It has a positive charge. • Neutron – a small particle within the nucleus which has a neutral charge. • Electron – a small particle which is in shells outside the nucleus. It has a negative charge.

3. Periodic table continued • Atomic number – The number of protons within the nucleus of an atom. This is also how the modern periodic table is arranged. The atomic number also equals the number of electrons in an atom. • Atomic Mass – a unit created to show the mass of an atom. • Atomic symbol – the letters that represent an element.

4. Inside the Square 4  atomic number Be -> atomic symbol Beryllium -> elements name 9.012 ->atomic mass

5. Reading the Periodic Table • An elements characteristic properties can be determined by where it lies on the periodic table. • Group or Family – The vertical columns of the periodic table. The elements in a column share properties, and have the same number of valence electrons. • Period – The horizontal rows across the periodic table.

6. Valence electrons • These are the electrons in the outermost shell of an atom. • They are responsible for bonding. • The number of valence electrons goes up in a period from left to right on the periodic table. • They determine whether an element gives up, shares, or accepts electrons.

7. Metals • The majority of elements on the periodic table are metals. • Chemists classify elements as metals based on their physical properties. These include: Shiny or dull hardness Malleability – the ability to be shaped or molded. Ductility – the ability to be drawn out, or pulled into a wire.

8. Chemical and other Properties • Other properties of metals include electrical conductivity, and magnetism. • Chemical properties – • Reactivity – The speed or ease at which an element combines or reacts with other compounds. Some metals are extremely reactive, others are nearly nonreactive. • Alloys – metals that are combined to take advantage of their properties.

9. Alkali Metals • The alkali metals are the metals of group 1. • They are the most reactive elements. • They are never found by themselves in nature. • 1 valence electron

10. Alkali Earth Metals • These are the metals of group two. • They are also very reactive. • They are hard, bright white and good conductors of heat and electricity. • Two valence electrons.

11. Transition Metals • Groups 3-12 – form a bridge from the very reactive metals on the left to the nonreactive metals on the right. • They very in the number of valence electrons. • These are the majority of the metals we use.

12. Metals in Mixed groups and Lanthanides and Actinides • Mixed group metals are in groups 13 thru 16. • They contain three to six valence electrons according to their group. • Lanthanides – are soft, malleable, shiny metals with good electrical conductivity. • Actinides – very rare, and most can only be produced in laboratories.

13. Non-metals and Metaloids • Non-metals are elements that lack the properties of metals. Most are gases at room temperature. • Physical properties – in addition to being mainly gases, most of the non-metals have low boiling points. They have opposite properties of metals. • Chemical properties – very non-reactive.

14. Compounds of Non-metals • Because they are very unreactive, metals usually bond with non-metals, with their valence electrons moving to the non-metals. • Group 18 elements generally do not react or form compounds with other elements. • Diatomic molecules – are compounds formed between the same elements.

15. Carbon Family • Most living things are made from carbon. • Group 14/4 has 4 valence electrons. Nitrogen Family • The nitrogen family, or group 15/5 has 5 valence electrons. Oxygen Family • The oxygen family is group 16/6 with six valence electrons.

16. Halogen Family • Group 17/7 has 7 valence electrons. This is the most reactive group of non-metals. Noble Gases • Group 18/8 has 8 valence electrons. This is the least reactive group. All of them are gases. Metalloids • Metalloids are the elements along the zigzag line. They have a varying ability to conduct electricity.

17. Elements From Stardust • Plasma – the so called fourth state of matter, plasma has its atoms stripped of electrons and are packed close together. • When the plasma atoms collide they create nuclear fusion, combining the plasma nuclei, to form heavier elements. • Hydrogen collides to form Helium, which collide to form Beryllium, etc • The heavier elements come from larger stars that contain more energy.