Pearson Chemistry Notes Essay

1. i. All atoms are composed of diminutive indivisible pinpoints called atoms. 1. ii. Atoms of the same element are identical. The atoms of any one element are different from those of any other element 1. iii. Atoms of different elements dismiss physically mix together or can chemically intermingle in simple whole-number ratios to form compounds 1. iv. Chemical reactions occur when atoms are quarantined from each other, joined, or rearranged in a different combination. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.Sizing up the Atom Atoms are very miniature the radii of most atoms fall mental capacityhin the range of 5 x 10-11 m to 2 x 10-10m atoms can be seen in scanning negatron microscopes atoms can be moved 4. 2 complex body part of the Nuclear Atom Overview Lots of Daltons theory is accepted excerpt that atoms can be divided Atoms can be divided into ternion subatomic particles Protons Neutrons El ectrons Subatomic Particles Electrons Discovered by UK physicist J. J. Thomson (1856-1940) Are negatively superaerated subatomic particles. Thomsons Experiment passed electric current through gasses at low pressure.Sealed the gases in glass tubes fitted at both ends with alloy disks called electrodes electrodes connected to source of electricity one electrode called the anode became positively bitchd other electrode, called cathode, became negatively charged resulted in glowing beam called Cathode Ray that traveled from cathode to anode. Findings cathode dig is deflected by electrically charged metal plates positively charged plate attracts the cathode ray negatively charged repels it Thomson knew that opposites attract hypothesized that a cathode ray is a stream of negatively charged particles moving at luxuriously speed called particles corpuscles.Later called electrons Millikans Experiment US physicist Robert A. Millikan (1868-1953) carried out experiments to call up the q uantity of an electrons charge. Oil drop experiment suspend negatively charged oil droplets between two charged plates. and so changed voltage on the plates to see how it affected the droplets rate of falling he found that the charge on each oil droplet was a multiple of 1. 60 x 1019 coulomb meaning it was the charge of an electron calculated electrons upsurge Millikans determine for electron charge and mass are similar to those accepted today.An electron has one unit of negative charge and its mass is 1/1840 the mass of a hydrogen atom Protons and Neutrons Four simple ideas about proposition and electric charges 1. Atoms have no net electric charge deaf(p) 2. Electric charges are carried by particles of matter 3. Electric charges always equal in whole-number multiples of a single basic unit that is, there are no fractions of charges. 4. when given a number of negatively charged particles combines wit an equal number of positively charged particles, an electrically neutral par ticle is formed.