Relative atomic mass - A r Just another way of saying how heavy different atoms are compared with the mass of one atom of carbon – 12 (regular carbon!)

Slides:

Advertisements

Similar presentations

4.3: HOW ATOMS DIFFER ATOMIC NUMBER

Advertisements

Chapter 11B Notes Determining Isotope Masses. Intro What is the mass of an atom with 6 protons and 6 neutrons? 12 What is the mass of an atom with 6 protons.

Mass Measurements In Chemistry Calculating Formula Weight.

OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM

1 Average Atomic Mass Chemistry Notes. 2 Relative Atomic Mass  Masses of atoms expressed in grams are very small, for example: One atom of Oxygen-16.

Atomic Mass The Mole Molecular Weight Unit 8 – Chemical Quantities 1.

ISOTOPES and RELATIVE ABUNDANCE What is an isotope? What is relative abundance?

Mass Number Atomic Number equals the # of... NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE POSITIVE CHARGE NEUTRAL CHARGE ATOM.

Isotopes Atoms of the same element that different mass numbers

Quiz: March 8 Balance the following equations: K2O + H2O -> KOH

The Mole—Quantifying Equations.  The mass of a single atom is far too small in grams to use conveniently.  Chemists use the unit called the unified.

Noadswood Science, Mass, Moles & Formula  To know how to calculate formula mass and work out the percentage of an element within a compound Saturday,

isotope Are atoms of the same element that have different masses. Due to a different number of neutrons in the nucleus.

Atomic Weight What does it mean?. The Mass of an Atom The mass of an atom is measured in atomic mass units (amu) aka Dalton. The atomic mass of an atom.

THE ATOM Counting. The Atom  Objectives Explain what isotopes are Define atomic number and mass number, and describe how they apply to isotopes Given.

27/05/2016 Relative mass formula, atomic mass, and empirical formula.

Quantitative Chemistry (Part 1) Isotopes Standard Atom for Mass Relative Atomic Mass Formula Mass Percentage Composition.

NOTES – 4.3: Atomic Number, Mass Number, Isotopes and Atomic Mass.

Isotopes and Ions.

More about isotopes Atomic mass vs average atomic mass or atomic weight.

& Average Atomic Mass  Atoms with the same number of protons (they are the same element) but different number of neutrons.

 Atomic Number- the number of protons in the nucleus of an atom of that element  Ex: Hydrogen atoms have only one proton in the nucleus, so the atomic.

Proton, Neutron, Electron Counting Protons (p + ) are positively charged and located in the nucleus The number of protons in each atom can be found on.

Isotopes Atoms of the same element with different mass numbers. Mass # Atomic # Nuclear symbol: Hyphen notation: carbon-12 Courtesy Christy Johannesson.

Using Isotope Data to Find a Weighted Average.  Each isotope will have two values associated with it.  Mass of Isotope  Percent Abundance (% found.

Isotopes and Average Atomic Mass Vocabulary: 1.isotope 2.percent abundance 3.average atomic mass “Marilyn Monroe”, Andy Warhol, 1962.

…AND THE AVERAGE ATOMIC MASS Isotopes. PG 88 GENERAL- ATOMS OF THE SAME ELEMENT BUT HAVE DIFFERENT AMOUNTS OF NEUTRONS IN THE NUCLEUS PAGE 54 PRE AP ATOMS.

Atomic Mass. Masses in amu Only carbon-12 has an atomic mass exactly equal to its mass # One atomic mass unit (amu) is defined as 1/12 the mass of a carbon-12.

Isotopic Abundance SCH 3U. Atomic Mass The mass of an atom (protons, neutrons, electrons) Relative Atomic Mass: An element’s atomic mass relative to the.

Counting atoms. atomic number - # of protons in atom of an element identifies element tells also # of e- Au, K, C, V.

Average Atomic Mass. Relative Atomic Masses  Masses of atoms (in grams) are very small, so for convenience we use relative masses.  Carbon-12 is our.

Unit 3: Atomic Structure. A. Subatomic Particles Most of the atom’s mass (Mass Number) NUCLEUS ELECTRON CLOUD PROTONS NEUTRONS ELECTRONS POSITIVE CHARGE.

How Atoms Differ. a. Properties of Subatomic Particles ParticleSymbolLocationRelative Charge Relative mass Actual mass (g) Electron Proton Neutron.

Chemistry.  Atomic Number  Mass Number  Isotopes  Atomic mass unit  Atomic mass.

An Atom is ……………. An Element is …………... A Compound is ………….

Isotopic Abundance Pages Thinking question Why are there decimal places for atomic masses on the periodic table if protons and neutrons have amu.

Structure of an Atom Atoms are composed of 3 subatomic particles: 1.Protons (p + ) – Positively charged, found in the nucleus, number of protons determines.

Section 6.1 Atoms and Moles 1.Students will be able to describe the concept of average mass. 2.Students will be able to demonstrate how counting can be.

Average Atomic Mass ► Average Atomic Mass – the weighted average of the masses of the isotopes of an element ► Every element is composed of several naturally.

IC5.1.4 Calculations © Oxford University Press Calculations.

Unit 3 Atomic Structure and Periodicity. Dalton’s Atomic Theory 1.All matter is composed of _____________. 2. Atoms of the same element are _______________.

Essential Question: How do atoms of the same element differ?

1 The Atom Atomic Number and Mass Number Isotopes.

Same Element Different Atom- Isotopes All atoms of a particular element are not exactly alike. Some elements have atoms with different masses (isotopes)

You’re going to need to get your pens ready for this one! Calculations in chemistry And quickly finishing off metallic structures.

Warm-Up -Write the correct Nuclide Symbol for the following elements: *19 p+, 20 n *82 e-, 125n *Mass # 238, neutrons= 146.

Rules recap! A small number just talks about the element it is behind. E.g. O2 = 2 x O Small numbers outside the bracket mean multiply everything inside.

Isotopes and Atomic Mass

SNC1D Isotopes.

ATOMIC STRUCTURE THE NUCLEUS: 1) THE PROTON:

Calculating Atomic Mass

Average Atomic Mass In nature, most elements are a mixture of different isotopes The mass of a sample of an element is a weighted average of all the isotopes.

Calculating Average Mass

Relative Formula Mass Noadswood Science, 2016.

A B 21085At Fe Mo 5827Co 3216S Pb4+ Symbol

Isotopes and Average Atomic Mass

Isotopes and Ions Section 3-3 Continued.

Standard Atomic Weights on Periodic Table (red numbers) are found through the terrestrial (Sol III) relative abundances of the masses (in amu) of the isotopes.

Mass of Individual Atoms

Standard Atomic Weights on Periodic Table (red numbers) are found through the terrestrial (Sol III) relative abundances of the masses (in amu) of the isotopes.

Atomic Masses 16.2.

Isotopes Atoms of the same element with a different number of neutrons

Atomic Structure Atoms make up elements

Atomic Math Calculations

Introduction to Atomic Structure

Chemicals of the Natural Environment.

The atomic number tells us:

Presentation transcript:

Relative atomic mass - A r Just another way of saying how heavy different atoms are compared with the mass of one atom of carbon – 12 (regular carbon!) Mass number Q. What does the atomic mass number represent? A. Total number of protons and neutrons found in an atoms nucleus Atomic number Number of protons present

Another handy trick you can do with the periodic table Mass number Atomic number You can work out how many neutrons an element has by subtracting the proton number from the mass number!! So how many neutrons:

Relative atomic mass - A r ElementArAr H1 C12 O16 Mg24 Cl35. Table.1. Different elements and their different A r Relative atomic mass is easy!! It’s the same value as the mass number – it just sounds scarier! So what does this tell us about Mg and H?

Relative formula mass - M r To find the relative formula mass (M r ) of a compound, you just add together the A r values for all the atoms in its formula. Example 1: Find the M r of carbon monoxide (CO). The A r of carbon is 12 and the A r of oxygen is 16. So the M r of carbon monoxide is = 28. Example 1: Find the M r of carbon monoxide (CO). The A r of carbon is 12 and the A r of oxygen is 16. So the M r of carbon monoxide is = 28. O 16 8

Relative formula mass - M r Example 2:Find the M r of sodium oxide-Na 2 O The A r of sodium is 23 and the A r of oxygen is 16. So the M r of sodium oxide is (23 x 2) + 16 = 62.

Carbon dioxide Sulphur dioxide SO 2 Calcium carbonate CaCO 3 Sodium hydroxide NaOH Sulphuric acid H 2 SO 4 Hydrochloric acid HCl Copper sulphate CuSO 4 Magnesium chloride MgCl 2 Sodium carbonate Na 2 CO 3 Find the M r of these:

ATOMIC MASS AND AVERAGE ATOMIC MASS u Atomic Mass = used to numerically indicate the mass of an atom in its ground state, it is expressed in the non SI unit of u u u = refers to unified atomic mass unit (formerly known as atomic mass unit or amu) u 1 amu = 1/12 the mass of carbon-12 atom, u therefore the mass of C-12 atom is made equal to 12 amu

Carbon-12 atom is an isotope of carbon 1 amu = 1.66 x g Note that: Atomic mass of 12 C = mass of p + mass of n + mass of e Mass of e = 1/1800 of mass of p and n so it is negligible making the equation

Atomic mass of 12 C = mass of p + mass of n Atomic mass vs. Average atomic mass For carbon it is 12 u not u  Used to relate the fact that the numerical value assigned to each element in the periodic table reflects the average abundances of the atoms that compose a naturally occurring element  Related to isotopes  For carbon it is u  Chemists often will use the term “atomic mass” when they are actually referring to average atomic mass of an atom.

Average Mass of Isotopes Isotopes are naturally occurring. Isotopes are naturally occurring. The mass # of an element (periodic table) is the weighted The mass # of an element (periodic table) is the weighted avg. of allisotopes that exist in nature. avg. of all isotopes that exist in nature. - abundance of isotope is just as important as mass! - abundance of isotope is just as important as mass! Ex... Ex... Natural copper (Cu) consists of 2 isotopes... Natural copper (Cu) consists of 2 isotopes... Copper - 63 (mass = g/mole) Copper - 63 (mass = g/mole) Copper - 65 (mass = g/mole) Copper - 65 (mass = g/mole) 69% 69% 31% 31% To calculate avg. mass... To calculate avg. mass... mass x abundance for each isotope Step 1 : Step 2 : add the two values from step 1 together x.69 = x.31 = g/mole

Ex... Ex... Three isotopes of Oxygen: Three isotopes of Oxygen: Oxygen - 18 Oxygen - 18 Oxygen - 16 Oxygen - 16 Oxygen - 17 Oxygen - 17 The avg. mass (from P.T.) is closest to 16, therefore, The avg. mass (from P.T.) is closest to 16, therefore, Oxygen-16 is the isotope that is most abundant in nature % 0.037% 0.204% The average mass of an element is closest to the isotope The average mass of an element is closest to the isotope that is mostplentiful in nature. that is most plentiful in nature.

Working with Weighted Averages & Calculating Average Atomic Mass Read page 165 of your text and make short notes.