chemistry (please send help) Flashcards
Who was Dmitri Mendeleev?
A scientist who organised the elements of the periodic table by atomic mass leaving room for undiscovered elements and predicting their properties based on their locations on the periodic table.
What are the groups in the periodic table?
vertical rows in the periodic table which show the number of valence electrons for each element.
The further down you go in a group…
…the greater the reactivity
What are the periods in the periodic table?
Horizontal rows going across the table telling you the number of shells each element has.
How many groups and periods are in the periodic table
18 groups and 7 periods
what are the three different blocks in the periodic table?
metal
non-metals
metalloids
what are at least three characteristics of metals?
- malleable
- ductile (can be drawn out into long thin wire)
- good conductors of heat and electricity
- high melting and boiling points
- are shiny
what are at least three characteristics of non-metals?
- brittle
- dull
- have low melting and boiling points
- poor conductors of heat and electricity
what are metalloids?
in between metals and non-metals; tend to look like metals but behave like non-metals.
Describe the composition of an atom
Proton (positive)
Neutrons (neutral) - in nucleus
electrons (negative) outer shells
what is the role of each subatomic particle in an atom?
protons and neutrons have opposite charges and attract. neutrons release a neutral charge which stabilizes the atom
what is the relative atom mass of each subatomic particle?
proton - 1
neutron - 1
electron - 1/1840
describe the electron arrangement for both light and heavy elements
heavy elements - 2, 8, 18, 32
light elements - 2, 8
atoms aim to fill their outermost shells (8 electrons based on the octet rule)
define electron configuration
the placement of electrons in the outer shells of an atom
what happens to metals when bonding?
metals tend to loose electrons to have a full outermost shell and gain a positive charge. (cations)
what happens to non-metals when bonding?
non-metals tend to gain electrons to fill their outermost shell giving them a negative charge. (anions)
define reactivity
the reactivity of an atom is determined by its willingness to gain or loose electrons.
explain ionic bonding
positively charged cations are attracted to negatively charged anions - this attraction is ionic bonding.
explain covalent bonding
when two non-metals bond neither element wants to loose electrons so both elements form a molecule by sharing electrons
describe the characteristics of group 1 elements
- alkali metals
- soft and low density
- highly reactive due to one valence electron
- react well with group 17 elements forming salts
- reacts violently with water
describe the characteristics of group 2 elements
- alkaline metals
- shiny silvery white
- low melting and boiling points
- reactive (not as reactive as group 1)
- react with group 17 forming metal salts
describe the characteristics of group 17 elements
- halogens
- mostly gas at room temperature (one liquid one solid)
- become darker going down the group
- react with other substances to gain an electron to fill valence shell
describe the characteristics of group 18 elements
- Nobel gases
- colorless and odorless
- very unreactive
define monatomic
generally metallic elements which exist as individual atoms
