Elements and their properties

1. Elements and their properties

2. Section 1: Metals

3. Properties of Metals • Discovered gold 6,000 years ago • Metals found left of the stair- step line • Common properties- good conductors of heat and electricity, all but Mercury (Hg) are solid at room temperature. Reflect light (called luster), are malleable, and ductile.

4. Properties of Metals

5. Bonding in metals • Ionic bonding- have 1- 3 electrons in their outer energy levels (remember all atoms are trying to achieve 8 electrons). When metals combine with nonmetals, metals lose electrons • Easier to lose 1- 3 electrons than to gain 5-7. • Take on the electron structure of the nearest noble gas.

6. Bonding in Metals • Metallic Bonding- positively charged metallic ions are surrounded by a cloud of electrons. • Outer level electrons not held tightly by nucleus but rather move freely through the metal ions. • Responsible for the properties of metals- metal does not break because the ions slide past each other within their electron clouds. Metals conduct electricity because outer- level electrons are weakly held.

7. The alkali metals • Group 1 • Shiny, malleable and ductile • React rapidly and violently with oxygen and water • One electron in outer energy level • Becomes positively charged in ionic bonds • Francium is radioactive, meaning that the nucleus breaks down and gives off particles and energy. http://www.youtube.com/watch?v=m55kgyApYrY

8. The alkaline earth metals • Group 2 • Shiny, malleable, and ductile • Combine readily with other elements- not found alone in nature • Two electrons in outer energy level • Has a +2 charge in ionic bonds

9. Transition Elements • Elements in groups 3- 12 • Occur in nature as uncombined elements • Iron, cobalt, and nickel known as the “iron triad” • Group 11- copper, silver, and gold. Stable, malleable, found as free elements in nature. Known as “coinage metals” • Group 12- zinc, cadmium, and mercury. Used in protective coatings. Mercury accumulates in the body and is dangerous and can be fatal.

10. Inner transition metals • Two rows disconnected from the rest of the periodic table. • Only done to save room • Lanthanides- first row, elements 58- 71 • Actinides- second row, elements 90- 103 • All are radioactive and unstable. • Uranium- used in nuclear reactors and weapons

11. Section 2- nonmetals

12. Properties of nonmetals • Typically gases or brittle solids are room temperature. Not malleable or ductile. Most do not conduct heat or electricity, are not shiny. • All found to the right of the stair step line except for hydrogen. • Only group 18 is made of all nonmetals.

13. Bonding in nonmetals • Form ionic and covalent compounds • In ionic bonds, gain electrons from metals, become negative. • When bonding with other nonmetals, form covalent bonds.

14. Hydrogen • 90% of all atoms in the universe are hydrogen • Hydrogen on its own forms a diatomic molecule • A molecule consisting of two atoms of the same element in a covalent bond • Highly reactive, has a single electron which it shares in covalent bonds. • Also forms ionic bonds in which it receives an electron from metals.

15. Halogens • Group 17 • Seven electrons in their outer energy level. • Needs to gain one electron from a metal • Forms salts, ionic compounds between halogens and metals. • NaCl • Fluorine most chemically active of all the elements. • Can be dangerous to work with

16. The Noble Gases • Group 18 on the periodic table • Exist as isolated atoms • Stable because they have 8 electrons in their outermost energy level • No known natural compounds • Used in neon lights

17. Section 3: Mixed groups

18. Properties of Metalloids • Form ionic and covalent bonds with other elements and have metallic and nonmetallic properties. • Are “semiconductors”- conduct electricity better than nonmetals but not as well as metals.

19. The Boron Group • Group 13 • Aluminum is the most abundant metal in the Earth’s crust • Have 3 electrons in outermost energy level • Lose 3 electrons in ionic bonding • Become +3

20. The Carbon Group • Group 14 • Have 4 electrons in their outermost energy level • Typically only form covalent bonds (too hard to lose or gain 4 electrons) • Carbon compounds are essential to life • Silicon has two allotropes, or different forms of the same element. • Used in semiconductors in electronics

21. Allotropes of Carbon • Graphite in pencil and diamonds both pure carbon • New allotrope discovered in 1980s called buckminsterfullerene (or “Bucky Balls”) • Used to make carbon nanotubes Graphite Diamond buckminsterfullerene

22. The Nitrogen Group • Group 15 • 5 electrons in outer energy level • Tend to share electrons and form covalent bonds

23. The oxygen group (chalcogens) • Group 16 • 6 electrons in outer energy level • Gain 2 electrons in ionic bonds • Become -2 • Oxygen forms diatomic molecules (O2) • Name chalcogen means “chalk former”

24. Synthetic Elements • Have over 92 protons • Except for technetium 43 and promethium 61 • Formed from smashing elements with particles on a heavy ion accelerator • Elements with over 92 protons are called transuranium elements. • All are synthetic and unstable • Make synthetic elements to understand the forces that hold nuclei together • Most do not last long- many last only fractions of a second.