chemical bonds Flashcards
(19 cards)
what is an atom
- electricity neutral
- eqal number of protons and electrons
what is an ion
- charged atom
- produced when atom lose or gain electrons
- unequal number of protons and electrons
what is a cation
metal atoms that have lost electrons to become positively charged (more protons than electrons)
what is an anion
- non-metal atoms that have gained electrons to become negatively charged (more electrons that protons)
how are ionic compounds formed
ionic compounds form when a cation and an anion join together by an ionic bond
what is a polyatomic ion
- ionic compounds can contain ions consisting of groups of atoms rather than a single atom
properties of ionic compounds
-all ionic compounds form lattices and crystals when solid
- ioinic formula is the simplest ration of the number of ions. ionic compounds do NOT form discrete molecules
-when solid the do not conduct electricity
- dissolved and molten- do conduct electricity (because the lattic breaks up and the ions (charged particles) are free to move)
-ionic compounds are brittle - they shatter when they are hit
what is covalent bonding
a covalent bond = a pair of shared electrons
sometimes two atoms share more than one pair of electrons
when does covalent bonding occur
covalent bonding forms when non-metal atoms share electrons to fill up their outer shell
what is a small covalent structure
-simple covalent structures have just a few atoms joined together - small discrete molecules
-can be gases, liquids or solids
-low melting and boiling points
giant covalent structures
-sometimes millions of atoms are joined together by covalent bonds
-this produces a rigid 3Dnetwork called a giant lattice. a diamond is a 3D network solid
what are different arrangements of the same atom called
allotropes
what is metallic bonding
-atoms of metals are tightly packed together in a giant lattice
-the outer electrons separate from their atoms and become delocalized creating a ‘sea of electrons’. the atoms become positive ions and are attracted to the electrons
-this attraction is called metallic bonding and is the reason why the positive metal ions do not repel each other
ionic bonding
metal + nonmetal
covalent bonding
nonmetal + nonmetal
metallic bodning
metal + metal
law of conservation of mass
mass can neither be created nor destroyed during chemical reactions. thus, in chemical relations, the mass of the products must equal the mass of the reactants
what is the reactant
the starting substance
what is the product
the substance that is formed
