periodic table

Question 1

key features

Answer 1

written in order of atomic number- no. of protons

groups are vertical (18) and contain atoms that have the same no. of valence electrons and thus have similar chemical and physical properties

periods are horizontal and have one extra shell (energy level or layer of electrons)

Question 2

valency

Answer 2

the no. of other atoms it can combine with is determined by groups, the valency of an ion is the charge on the ion
the valency of an atom in a covalent compound is the no. of electrons it must gain to have a full outer shell

Question 3

ions - charged atoms

Answer 3

anions ( -ve) = gained valence e-

cations (+ve) = lost valence e-

Question 4

where are alkaline metals, alkaline earth metals, halogens, other non-metals - noble gases, metaloids, transition metals, poor metals on the periodic table

Answer 4

o

Question 5

halogens

Answer 5

non-metals, mostly gases, reactive

Question 6

noble gases

Answer 6

non-metals, gases, unreactive

Question 7

transition metals

Answer 7

metals, classic properties - shiny , malleable, durite, conductors

Question 8

EFFECTIVE NUCLEAR CHARGE

Answer 8

the atomic radius, ionic radius, electronegativity and ionisation energy trends in the periodic table are a results of ENC (electron attracting power of the nucleus)

Question 9

ENC - across a period

Answer 9

moving across a period (left to right)
the energy level (or shell) remains the same
but the number of protons in the nucleus increases and thus it has more of a positive charge

this means the ENC (electron attracting power of the nucleus) increases and thus the electrons are more tightly held at the right of a period than the left

more protons = more attracting power

same interference from inner electrons
ENC increases across a period

Question 10

ENC - down a group

Answer 10

• the valence energy level (shell number) increases
  outer electrons are further from the nucleus
  inner electrons shield outer electrons from the nucleus

the ENC decreases down a group and so outer electrons are less tightly held
down a group= decrease in ENC less hold on outer electrons

Question 11

ENC

Answer 11

by combining both concepts- electrons are most tightly held in the elements at the top right of the PT and less tightly held at the lower left of the PT

Question 12

Atomic radius

Answer 12

atomic radius is the size of the atom. When electros are tightly held they move closer to the nucleus, the atom becomes physically smaller

increase ENC - squish electrons closer = smaller atomic radius

more shells - less ENC = larger atomic radius

Question 13

atomic radius in a period

Answer 13

atomic size decreases across a period. The electrons in the outer shell are approximately the same energy level. The attracting power of the nucleus is increasing due to the increasing number of protons

Question 14

atomic size down a group

Answer 14

• the outershell number increases so the electrons are further away from the nucleus
  the attraction from the nucleus is shielded by inner shells
  electrons are held more closely

Question 15

ionic radius

Answer 15

an ions radius decreases across a period and down a group. However the charge imbalance on the ion changes the size of the ion relative to the atom

i) positive ions have more protons than electrons this means a greater “pulling power” and thus a smaller ion than the atom
cations —> metal

ii) negative ions hae more electrons than protons- this means less “pulling power” and therefore a larger ion than the atom
anions —-> non-metals

Question 16

ionisation energy

Answer 16

ionisation energy is the energy required to remove an electron from the atom

Question 17

what is first and second ionisation energy

Answer 17

first ionisation energy is the energy required to remove the first electron
second ionisation energy is the energy required to remove the second electron ect

IF an electron is tightly held it will require more energy to remove it. These atoms have high ionisation energy. A single electron in the valence shell is easy to remove (low ionisation energy)

Question 18

trends in 1st ionisation energyme

Answer 18

moving across a period shows an increase in ionisation energy because of the ENC increase
it whos that moving down a group decreases the ionisation energy as ENC decreases

the first electron is the easiest to remove as it has the lowest ionisation energy and is in the outermost shell.

The next 8 electrons are in the n-2 shell and are more difficult to remove. Finally the last 2 require way more energy as they are in the innermost shell, n=1 are closer to the nucleus and the electrostatic energy is much greater.

Question 19

electonegativity

Answer 19

electronegativity is the electron attracting ability of the nucleus of the atom
Electronegativity increases across a period and decreases down a group (generally)

Question 20

metalic character

Answer 20

the metalic character of a substance is its tendency to give up its electrons (link to the fact that all metals form positive ions when they bond)

metalic character trends are opposite to electronegativity trends

increasing metalic character across a period
increasing metalic character down a group on the legt
increasing non-metalic character up a group right

Question 21

ionic bonding

Answer 21

metal and non-metal react by accepting or donating electrons producing ions that are attracted to each other

Question 22

sharing electrons

Answer 22

COVALENT BONDING - two non-metals

Question 23

ionis substances

Answer 23

common physical properties

• very strong bonds holding atoms together, this gives them very high MP and BP
• will conduct electricity when melting (molten) or dissolved but not as a solid
• they are brittle

ionic substances - metals and non-metals forming a 3D lattice strucutre. There are two types of atoms bond because they have transferred an electron (s) and have opposite charges. Opposites attract (electrostatic attraction) - WHAT AN IONIC BOND ACTUALLY IS

Question 24

IONIC BONDS

Answer 24

an ionic bond is the force of attraction (electrostatic attraction) that holds together pos and neg ions- opposites attract

it forms when atoms of a metallic element give up electrons to atoms of a non-metallic element - metals lose valence e- , non-metals gain valence e-

Question 25

ionic bonds metals

Answer 25

metals atoms lose electrons to non-metalic atoms and so become positively charged metal ions (cations). There are more protons than electrons so a charge inbalance exists

Question 26

ionic bonds non-metals

Answer 26

non-metal atoms gain electrons from metal atoms and so become negatively charged non-metal ions(anions). There are more electrons than protons and so a charge imbalance exists

THUS after a cation and anion have been formed the two particles bond in large numbers to form a compound with a lattice structure

Question 27

forming ionic compounds

Answer 27

atoms are at their most stable when their valence shell is full.
ionic compounds- anion and cation combine in proportions to make an overall neutral compound
polyatomic ions (C03)2 use swap n drop

Question 28

naming ionic substances

Answer 28

ionic substances have a two word name- the first word is the name of the cation (+ion) followed by the name of the anion (-ion) with an “ide” on the end

Question 29

covalent bonding

Answer 29

sharing pair of valence electrons by two non-metals
bonds holding molecules to each other are weak so covalent substances have low MP and BP
generally gases at room temp
dont conduct electricity because no charged particles/ free electrons

naming - first name of the more metalic element, then less metalic element with ide on the end

Question 30

metalic substances

Answer 30

in metalic bonding, the valence electrons of each metal atom have been delocalised, meaning that electrons can move freely throughout the metal structure
free electrons allow excellent electrical and thermal conductivity
bonding strength is med- strong causing a range of MP and BP
naming use the name of the element for pure substances

Question 31

ionic bonding

Answer 31

electrostatic attraction between oppositely charged ions (charged atoms) form a rigid 3D stucture
MP and BP is high
swap and drop
metals give/ transfer/lose electrons to non-metals to become a positively charged ion= cation

non-metals gain electrons to become a negatively charged ion= anion

cations and anions bond to form large lattice stuctures
naming- first write the name of the cation, then use the name of the anion with ide on the end

Question 32

polyatomic ions

Answer 32

group of bonded atoms that as a group have a charge
ratio of atoms in an ion must remain constant thus brackets used if more than one ion
ions that have a 2+ or 3+ charge form stronger ionic bonds than 1+ions

Question 33

bonding and properties

Answer 33

strong intramolecullar bond (only broken during a chemical reaction NOT state change)

“weak” intramolecullar force broken during a state change holding molecules to each other
for an electrical current there must be free moving charged particles - electrons or ions

Question 34

electrical conductivity - ionic bonding

Answer 34

tightly held by electrostatic forces in a 3D structure so electrons/ charged particles can’t move (electricity not conducted)
but when the structure is broken by melting/dissolving the charged ions can more therefore electricity is conducted

Question 35

electrical conductivity - covalent substances

Answer 35

no charged particles - electricity not conducted

Question 36

EC - metalic substsnces

Answer 36

generates cations in a sea of electrons (delocalised electrons). This movement promotes electrical conductivity very effectively

Question 37

covalent bonding

Answer 37

between 2 or more non-metals
share valence electrons to obtain a stable config.
a shared pair of electrons= covalent bond
produces - covalent molecules (mostly)
- covalent network lattices (diamonds)
draw using lewis diagrams
the number of covalent bonds an atom makes is the number needed to reach 8 ( 8 - number of valence e-)

Question 38

single covalent bonds (1 shared pair)

Answer 38

1 shared pair= 1 covalent bond
double 2 shared paird
triple - 3 shared pairs

Question 39

summary ionic bonding

Answer 39

high BP and MP because of electrostatic attraction is very strong and regular 3D lattice is formed

no electrical conductivity because ions are very tightly bound (not moveable) but electrical conductivity will occur when dissolved and melted - charged particles able to move
soluble (mostly) because partial charges on water molecules are attracted to ions

brittle because changing the shape of the lattice forces charges together and it splits - hard bc bonding is strong

Question 40

metallic bonding

Answer 40

the structure is strong but w some movement
MP and BP are med-high
high electrical conductivity because they are delocalised valence electrons are free to move
insoluble
hard, malleable and ductile (their shape can be changed ) bonding is strong by the “sea” of electrons allows some movement of cations in the lattice

Question 41

covalent bonding

Answer 41

lower melting and BP because intramollecular forces between molecules are low
no electrical conductivity because there are no charged particles present
covalent molecules w partial charge will dissolve in water, no partial charge will not dissolve
most are liquids or gases (some soft solids) weak IMF

Question 42

covalent network

Answer 42

high MP and BP because bonding is very strong and 3D lattice is usually formed
no electrical conductivity- valence electrons contained in stable covalent bonds (not moveable)
insoluable
very hard lattice, giant molecules or network solid - many comprised of carbon

Question 43

chemical reactions

Answer 43

use arrow
heat light gas sound may also be produced
chemical and physical changes