NonmetalsNonmetals

Section 20.2 and 20.3Section 20.2 and 20.3

NonmetalsNonmetals

Nonmetals- gases or brittle solids at Nonmetals- gases or brittle solids at room temperature. room temperature. – not malleable or ductile. not malleable or ductile. – do not conduct heat or electricity well do not conduct heat or electricity well – not shiny not shiny

Nonmetals don’t conduct electricity Nonmetals don’t conduct electricity because- electrons are strongly because- electrons are strongly attracted to the nucleus attracted to the nucleus

NonmetalsNonmetals

Nonmetals- gain electrons to form Nonmetals- gain electrons to form anionsanions

Can form either covalent or ionic bondsCan form either covalent or ionic bonds Diatomic- molecule that consists of two Diatomic- molecule that consists of two

atoms of the same element covalently atoms of the same element covalently bonded bonded – Includes HIncludes H22 Cl Cl22 F F22 N N22 O O22 Br Br22 I I22

Hydrogen is diatomic because it is very Hydrogen is diatomic because it is very reactive. reactive. – Bonding makes it more stableBonding makes it more stable

NonmetalsNonmetals

Halogens- nonmetals from group 17. Halogens- nonmetals from group 17. – very reactive. very reactive. – 7 valence electrons 7 valence electrons – form reactive diatomic molecules with form reactive diatomic molecules with

distinctive colors distinctive colors Sublimation- changing directly from a Sublimation- changing directly from a

solid to a vaporsolid to a vapor Noble gases- stable due to full outer Noble gases- stable due to full outer

energy levels. energy levels. – don’t make compounds naturally don’t make compounds naturally

Metalloid & AllotropesMetalloid & Allotropes

Metalloid- can form ionic or covalent Metalloid- can form ionic or covalent bonds. bonds. – properties of both metals and nonmetals properties of both metals and nonmetals

Allotrope- different forms of the same Allotrope- different forms of the same elementelement– have different molecular structures have different molecular structures

Semiconductor- element that Semiconductor- element that conducts electric current under conducts electric current under certain conditions- like Siliconcertain conditions- like Silicon

Diamond vs. GraphiteDiamond vs. Graphite

Both are made of carbon. Both are made of carbon. Diamond- clear, hardDiamond- clear, hard

– each C atom bonded to four other C each C atom bonded to four other C atoms forming a giant crystal. atoms forming a giant crystal.

Graphite- black powder with Graphite- black powder with hexagonal layers of C atoms. hexagonal layers of C atoms. – Each C is bonded to 3 other C. Each C is bonded to 3 other C. – Layers can slide past each other, so Layers can slide past each other, so

graphite is a good lubricant. graphite is a good lubricant.

Synthetic ElementsSynthetic Elements

Transuranium elements - elements Transuranium elements - elements that have an atomic number greater that have an atomic number greater than 92 (uranium). than 92 (uranium). – Synthetic (man made) and unstable Synthetic (man made) and unstable

Scientists make elements to gain an Scientists make elements to gain an understanding of the forces holding understanding of the forces holding the nucleus togetherthe nucleus together– To develop new technologiesTo develop new technologies